answer：To determine how many integers between 300 and 700 contain both the digits 2 and 5, we can break down the problem as follows:1. **Hundreds Digit Constraints:** - The hundreds digit can be 3, 4, 5, or 6.2. **Tens and Units Digits:** - The digits 2 and 5 must appear in either the tens or units place. - There are two possible arrangements for these digits: 25 or 52.3. **Calculating the Total Number of Integers:** - For each hundreds digit (3, 4, 5, 6), there are 2 possible arrangements of the digits 2 and 5 in the tens and units places. - Therefore, the total number of integers is 4 (hundreds digits) multiplied by 2 (arrangements), resulting in 8 integers.Thus, there are 8 integers between 300 and 700 that contain both the digits 2 and 5.

answer：First, I'll identify the number of boxes sold on each day based on the given relationships.Starting with Friday, Kim sold 600 boxes.On Thursday, she sold 1.5 times the number of boxes sold on Friday. So, Thursday's sales are 1.5 multiplied by 600, which equals 900 boxes.On Wednesday, she sold twice as many boxes as on Thursday. Therefore, Wednesday's sales are 2 multiplied by 900, resulting in 1800 boxes.Finally, on Tuesday, she sold three times the number of boxes sold on Wednesday. Thus, Tuesday's sales are 3 multiplied by 1800, which equals 5400 boxes.

answer：Okay, so I have this problem about two trains passing each other. Let me try to understand what's going on here. There are two trains, each 210 meters long, moving on parallel tracks but in opposite directions. One train is going at 90 km/h, and the other at 85 km/h. I need to find out how long it will take for them to pass each other completely.First, I think I need to figure out their relative speed. Since they're moving in opposite directions, their speeds should add up, right? So, if one is going at 90 km/h and the other at 85 km/h, the total speed between them is 90 + 85 = 175 km/h. That makes sense because when two objects move towards each other, their relative speed is the sum of their individual speeds.But wait, the lengths of the trains are given in meters, and the speeds are in kilometers per hour. I think I need to convert the speed from km/h to m/s to make the units consistent. How do I do that? I remember that 1 km is 1000 meters and 1 hour is 3600 seconds. So, to convert km/h to m/s, I can multiply by 1000/3600, which simplifies to 5/18.Let me calculate that. So, 175 km/h multiplied by 5/18 should give me the speed in m/s. Let's see: 175 * 5 = 875, and then 875 divided by 18 is approximately 48.61 m/s. Okay, that seems right.Now, I need to find out the total distance they need to cover to pass each other completely. Since both trains are 210 meters long, the total distance is 210 + 210 = 420 meters. That makes sense because each train has to cover its own length plus the length of the other train to pass completely.With the relative speed and the total distance, I can use the formula: time = distance / speed. So, time = 420 meters / 48.61 m/s. Let me calculate that. 420 divided by 48.61 is approximately 8.64 seconds. Hmm, that seems a bit quick, but considering they're moving pretty fast, maybe it's correct.Wait, let me double-check my calculations to make sure I didn't make a mistake. Starting with the relative speed: 90 km/h + 85 km/h = 175 km/h. Converting to m/s: 175 * 1000 / 3600 = 175000 / 3600 ≈ 48.61 m/s. That seems right.Total distance: 210 + 210 = 420 meters. Time = 420 / 48.61 ≈ 8.64 seconds. Yeah, that looks consistent. I think I did it correctly.So, the time it takes for the two trains to pass each other completely is approximately 8.64 seconds.

answer：Alright, so I have this problem about a red square being covered by 100 white squares. All the squares are the same size, and their sides are parallel to the red square's sides. The question is asking if it's always possible to remove one white square and still have the remaining 99 white squares completely cover the red square.Hmm, okay. Let me try to visualize this. If the red square is covered by 100 white squares of the same size, that means each white square is exactly the same size as the red one. So, each white square must be positioned in such a way that they overlap to cover the entire red square.Wait, but if all the white squares are the same size as the red square, how are they covering it? If you have multiple squares of the same size overlapping, they must be arranged in some pattern. Maybe they're arranged in a grid? Like, if you divide the red square into smaller squares, but since all white squares are the same size as the red one, that doesn't make sense.Oh, maybe they're overlapping in some way. So, each white square is placed such that it partially overlaps with the others. But how exactly?Let me think about the arrangement. If the red square is covered by 100 white squares, each white square must cover a portion of the red square. Since they're all the same size and aligned, perhaps they're arranged in a grid pattern where each white square is shifted slightly from the others.But wait, if they're all the same size as the red square, shifting them would mean that each white square is just overlapping the red square entirely. That doesn't make sense because then you wouldn't need 100 white squares to cover the red one; one would suffice.Hmm, maybe I'm misunderstanding the problem. The comment says that all the squares are identical, meaning all white squares are the same size as the red square. So, each white square is exactly the same size as the red square, and their sides are parallel.So, if you have 100 white squares, each the same size as the red square, covering it, how are they arranged? It must be that each white square is placed in a way that it's overlapping the red square, but in such a way that together, they cover the entire red square.But if each white square is the same size as the red one, how can they be arranged to cover the red square without just being on top of it? Maybe they're arranged in a grid pattern, but since they're the same size, they can't be smaller. So, perhaps they're arranged in a way that they're shifted by some fraction of their size.Wait, maybe they're arranged in a grid where each white square is shifted by 1/100th of the red square's side length. So, if you have 100 white squares, each shifted slightly, they can cover the entire red square.But then, if you remove one of them, would the remaining 99 still cover the red square? That depends on how critical that one square was in covering a particular part of the red square.If the squares are arranged in such a way that each one covers a unique part of the red square, then removing one might leave a gap. But if they overlap sufficiently, maybe removing one wouldn't leave a gap.Wait, but in the problem statement, it's asking if it's always possible to remove one. So, regardless of how the 100 white squares are arranged, can we always remove one and still have full coverage?I think the answer might be no, because it's possible to arrange the white squares in such a way that each one is necessary for full coverage. For example, if each white square covers a unique small region that no other white square covers, then removing any one would leave that region uncovered.But how can that be, since all white squares are the same size as the red square? If each white square is the same size as the red one, then each one must cover the entire red square, right? Because if you have a white square the same size as the red one, and it's aligned, then it must cover the entire red square.Wait, that can't be, because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But that seems contradictory to the problem statement, which is asking if it's always possible to remove one. Maybe I'm misunderstanding the arrangement.Wait, perhaps the white squares are not all covering the entire red square, but rather, each white square is a smaller square that, when combined with others, covers the red square. But the comment says all the squares are identical, meaning all white squares are the same size as the red square.So, each white square is the same size as the red square, and they are placed in such a way that together, they cover the red square. But since each white square is the same size as the red one, they must be overlapping the red square entirely.Wait, that doesn't make sense because if you have 100 white squares, each the same size as the red one, and they're all covering the red square, then each white square must be placed on top of the red square, overlapping it entirely. So, in that case, removing one white square would still leave 99 white squares covering the red square.But that seems too straightforward, and the problem is asking if it's always possible, which suggests that sometimes it might not be possible.Maybe I'm missing something. Perhaps the white squares are not all placed on top of the red square, but rather arranged in a way that each one covers a specific part of the red square.Wait, but if each white square is the same size as the red square, and their sides are parallel, then each white square must be placed such that it's either entirely covering the red square or not. If it's not entirely covering, then it's only partially overlapping.But if you have 100 white squares, each partially overlapping the red square, arranged in such a way that together they cover the entire red square, then removing one might leave a part uncovered.But how can a white square, which is the same size as the red square, only partially overlap it? If their sides are parallel, then the white square must either be entirely within the red square or overlapping it partially.Wait, no. If the white square is the same size as the red square, and their sides are parallel, then the white square must be either coinciding with the red square or shifted in some way.If it's shifted, then part of the white square would be outside the red square, but since the problem says that the white squares cover the red square, the parts of the white squares that are outside don't matter. So, each white square must cover some part of the red square, and together, they cover the entire red square.But if each white square is the same size as the red square, and they're shifted, then each one covers a different part of the red square.Wait, but how can a square the same size as the red square, when shifted, only cover a part of it? If you shift it by, say, half its size, then it would cover half of the red square.But if you have 100 white squares, each shifted by a small amount, they can cover the entire red square.But then, if you remove one, would the remaining 99 still cover the red square?It depends on how the shifting is done. If each white square is responsible for a unique small part of the red square, then removing one would leave that part uncovered.But if the shifting is done in such a way that each part of the red square is covered by multiple white squares, then removing one wouldn't leave any part uncovered.So, the answer depends on the arrangement of the white squares.But the problem is asking if it's always possible to remove one, regardless of the arrangement. So, if there exists an arrangement where removing any one white square would leave the red square uncovered, then the answer is no.But how can that be? If each white square is the same size as the red square, and they're arranged to cover it, then each white square must cover the entire red square, right? Because if you have a white square the same size as the red one, and it's aligned, then it must cover the entire red square.Wait, that can't be, because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But that seems contradictory to the problem statement, which is asking if it's always possible to remove one. Maybe I'm misunderstanding the problem.Wait, perhaps the white squares are not all covering the entire red square, but rather, each white square is a smaller square that, when combined with others, covers the red square. But the comment says all the squares are identical, meaning all white squares are the same size as the red square.So, each white square is the same size as the red square, and they are placed in such a way that together, they cover the red square. But since each white square is the same size as the red one, they must be overlapping the red square entirely.Wait, that doesn't make sense because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But the problem is asking if it's always possible to remove one, which suggests that sometimes it might not be possible. So, maybe the white squares are arranged in such a way that each one covers a unique part of the red square, and removing one would leave that part uncovered.But how can a white square, which is the same size as the red square, cover only a unique part of it? If it's the same size, it must cover the entire red square.Wait, maybe the white squares are arranged in a way that each one covers a different part of the red square, but since they're the same size, they must overlap.Wait, perhaps the red square is divided into smaller regions, and each white square covers one of these regions, but since they're the same size as the red square, they must overlap multiple regions.I'm getting confused. Let me try to think differently.Suppose the red square is divided into a grid of 100 smaller squares, each of size 1/10th the side length of the red square. Then, each white square is the same size as the red square, so it would cover 100 of these smaller squares.But if you have 100 white squares, each covering 100 smaller squares, then together they cover the entire red square. But if you remove one white square, you're removing coverage for 100 smaller squares. But since each smaller square is covered by multiple white squares, maybe removing one wouldn't leave any part uncovered.Wait, but if each smaller square is only covered by one white square, then removing that white square would leave that smaller square uncovered.But how can that be, since each white square covers 100 smaller squares, and there are 100 white squares, each covering 100 smaller squares, which would mean that each smaller square is covered by exactly one white square.So, in that case, removing one white square would leave 100 smaller squares uncovered, which would mean the red square is no longer fully covered.But that seems like a possible arrangement. So, in this case, it's not always possible to remove one white square without leaving the red square uncovered.But wait, in this arrangement, each white square is covering a unique set of 100 smaller squares, which is the entire red square. So, each white square is actually covering the entire red square, which contradicts the idea that each smaller square is only covered by one white square.Wait, no. If the red square is divided into 100 smaller squares, and each white square covers all 100 smaller squares, then each white square is covering the entire red square. So, removing one white square would still leave 99 white squares, each covering the entire red square, so the red square would still be fully covered.But that contradicts the earlier idea where each smaller square is only covered by one white square.I think I'm getting tangled up here. Let me try to clarify.If the red square is covered by 100 white squares, each the same size as the red square, and their sides are parallel, then each white square must be placed in such a way that it covers the entire red square. Because if they're the same size and aligned, they can't be smaller or shifted in a way that only covers part of the red square.Wait, but if you shift a white square by a small amount, it would still cover the entire red square, just overlapping it entirely. So, in that case, each white square is covering the entire red square, and removing one wouldn't affect the coverage.But then, why would the problem ask if it's always possible to remove one? It seems like it should always be possible because each white square is redundant in covering the entire red square.But maybe the arrangement is different. Maybe the white squares are arranged in such a way that each one covers a specific part of the red square, and together, they cover the entire red square, but no single white square covers the entire red square.Wait, but if each white square is the same size as the red square, and their sides are parallel, then each white square must cover the entire red square. Because if you have a square the same size as the red one, and it's aligned, it must cover the entire red square.So, in that case, each white square is redundant, and removing one wouldn't affect the coverage. So, it should always be possible to remove one.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe I'm missing something.Wait, perhaps the white squares are not all covering the entire red square, but rather, each white square is a smaller square that, when combined with others, covers the red square. But the comment says all the squares are identical, meaning all white squares are the same size as the red square.So, each white square is the same size as the red square, and they are placed in such a way that together, they cover the red square. But since each white square is the same size as the red one, they must be overlapping the red square entirely.Wait, that doesn't make sense because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But the problem is asking if it's always possible to remove one, which suggests that sometimes it might not be possible. So, maybe the white squares are arranged in such a way that each one covers a unique part of the red square, and removing one would leave that part uncovered.But how can a white square, which is the same size as the red square, cover only a unique part of it? If it's the same size, it must cover the entire red square.Wait, maybe the white squares are arranged in a way that each one covers a different part of the red square, but since they're the same size, they must overlap.Wait, perhaps the red square is divided into smaller regions, and each white square covers one of these regions, but since they're the same size as the red square, they must overlap multiple regions.I'm getting stuck here. Let me try to think of a specific example.Suppose the red square is divided into a 10x10 grid of smaller squares. Each white square is the same size as the red square, so it would cover the entire grid. If you have 100 white squares, each covering the entire grid, then removing one wouldn't affect the coverage.But that seems redundant. Why have 100 white squares if each one covers the entire red square? It must be that each white square is covering a specific part of the red square, not the entire thing.Wait, but if they're the same size as the red square, they can't cover only a part of it without overlapping entirely.I think I'm missing something here. Maybe the white squares are arranged in such a way that each one covers a specific part of the red square, but since they're the same size, they must overlap.Wait, perhaps the white squares are arranged in a way that each one covers a unique small region, but since they're the same size as the red square, they must overlap multiple regions.I'm not making progress here. Let me try to think differently.Maybe the key is that each white square covers the entire red square, so removing one doesn't affect the coverage. Therefore, it's always possible to remove one.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe there's a way to arrange the white squares such that each one is necessary for full coverage.Wait, but if each white square is the same size as the red square, and they're aligned, then each one must cover the entire red square. So, removing one wouldn't leave any part uncovered.Therefore, it should always be possible to remove one.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe I'm misunderstanding the problem.Wait, perhaps the white squares are not all covering the entire red square, but rather, each white square is a smaller square that, when combined with others, covers the red square. But the comment says all the squares are identical, meaning all white squares are the same size as the red square.So, each white square is the same size as the red square, and they are placed in such a way that together, they cover the red square. But since each white square is the same size as the red one, they must be overlapping the red square entirely.Wait, that doesn't make sense because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But the problem is asking if it's always possible to remove one, which suggests that sometimes it might not be possible. So, maybe the white squares are arranged in such a way that each one covers a unique part of the red square, and removing one would leave that part uncovered.But how can a white square, which is the same size as the red square, cover only a unique part of it? If it's the same size, it must cover the entire red square.Wait, maybe the white squares are arranged in a way that each one covers a different part of the red square, but since they're the same size, they must overlap.Wait, perhaps the red square is divided into smaller regions, and each white square covers one of these regions, but since they're the same size as the red square, they must overlap multiple regions.I'm going in circles here. Let me try to think of it mathematically.If the red square has area A, and each white square also has area A, then the total area covered by 100 white squares is 100A. But the red square only has area A, so there's a lot of overlap.If we remove one white square, the total area covered becomes 99A, which is still more than A. But area doesn't necessarily translate to coverage because overlapping areas are counted multiple times.But the question is about covering, not about the total area. So, even if the total area is more than A, the actual coverage might still be A.But if each white square is necessary to cover a specific part of the red square, then removing one might leave that part uncovered.But how can a white square, which is the same size as the red square, be necessary for a specific part? If it's the same size, it must cover the entire red square.Wait, maybe the arrangement is such that each white square covers a specific part of the red square, and no other white square covers that part. But since each white square is the same size as the red square, they must all cover the entire red square, making it redundant.I'm really confused now. Let me try to think of it differently.Suppose the red square is covered by 100 white squares, each the same size as the red square, and their sides are parallel. If I remove one white square, does the remaining 99 still cover the red square?If each white square is covering the entire red square, then yes, removing one wouldn't affect the coverage. But if each white square is only covering a part of the red square, then removing one might leave that part uncovered.But since each white square is the same size as the red square, and their sides are parallel, they must cover the entire red square. So, each white square is redundant in covering the entire red square.Therefore, it should always be possible to remove one white square, and the remaining 99 would still cover the red square.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe the answer is no, it's not always possible.Wait, but how? If each white square is covering the entire red square, then removing one wouldn't affect the coverage.I think I'm missing something here. Maybe the white squares are arranged in such a way that each one covers a unique part of the red square, and no other white square covers that part. But since each white square is the same size as the red square, they must all cover the entire red square, making it impossible for any part to be covered by only one white square.Therefore, it should always be possible to remove one white square, and the remaining 99 would still cover the red square.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe the answer is yes, it's always possible.Wait, but I'm not sure. I think I need to look for a specific example or a proof.Let me consider a simpler case. Suppose the red square is covered by 2 white squares, each the same size as the red square. Can I remove one and still have full coverage?Yes, because each white square covers the entire red square, so removing one would still leave the other covering the red square.Similarly, for 3 white squares, removing one would still leave 2, each covering the entire red square.So, in general, if you have n white squares, each covering the entire red square, then removing one would still leave n-1 white squares, each covering the entire red square.Therefore, the red square would still be fully covered.So, in the case of 100 white squares, removing one would still leave 99 white squares, each covering the entire red square. Therefore, the red square would still be fully covered.Therefore, it's always possible to remove one white square.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe I'm misunderstanding the problem.Wait, perhaps the white squares are not all covering the entire red square, but rather, each white square is a smaller square that, when combined with others, covers the red square. But the comment says all the squares are identical, meaning all white squares are the same size as the red square.So, each white square is the same size as the red square, and they are placed in such a way that together, they cover the red square. But since each white square is the same size as the red one, they must be overlapping the red square entirely.Wait, that doesn't make sense because if you have 100 white squares, each covering the entire red square, then removing one would still leave 99 white squares, each covering the entire red square. So, the red square would still be fully covered.But the problem is asking if it's always possible to remove one, which suggests that sometimes it might not be possible. So, maybe the answer is yes, it's always possible.Wait, but I'm not sure. I think I need to conclude based on my reasoning.Given that each white square is the same size as the red square and their sides are parallel, each white square must cover the entire red square. Therefore, removing one white square would still leave the remaining 99 white squares, each covering the entire red square. Hence, the red square would still be fully covered.Therefore, it's always possible to remove one white square.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe the answer is no, it's not always possible.Wait, I'm contradicting myself. Let me think again.If each white square is the same size as the red square and aligned, then each one covers the entire red square. Therefore, removing one wouldn't affect the coverage. So, it's always possible to remove one.But the problem is asking if it's always possible, which suggests that sometimes it might not be. So, maybe the answer is yes, it's always possible.Wait, I think I'm overcomplicating this. The key is that each white square covers the entire red square, so removing one doesn't affect the coverage. Therefore, it's always possible to remove one.So, the answer is yes, it's always possible to remove one white square and still have the remaining 99 cover the red square.But I'm not entirely confident. Maybe the answer is no, because if the white squares are arranged in a way that each one covers a unique part, but since they're the same size, they must all cover the entire red square.I think the answer is yes, it's always possible.

answer：First, I recognize that the number ( n ) is given as 9376.To determine the number of digits in ( n ), I will count each digit in 9376.Starting from the left, the digits are 9, 3, 7, and 6.Counting these, I find that there are four digits in total.Therefore, the number ( n ) has 4 digits.

answer：To determine the number of ways to choose a President, a Vice-President, and a Secretary from a group of 6 people, we can use the concept of permutations since the order of selection matters and each position must be held by a different individual.**Step 1: Choose the President**- There are 6 possible choices for selecting the President.**Step 2: Choose the Vice-President**- After selecting the President, 5 individuals remain.- Therefore, there are 5 possible choices for selecting the Vice-President.**Step 3: Choose the Secretary**- After selecting the President and Vice-President, 4 individuals remain.- Hence, there are 4 possible choices for selecting the Secretary.**Total Number of Ways**- Multiply the number of choices for each position:[ 6 times 5 times 4 = 120 ]Thus, there are 120 ways to choose a President, a Vice-President, and a Secretary from a group of 6 people.