The factors of 10 are 5 and 2. Note that the 5th multiple of 5 will bring a pair of 5s into the product, which means you couldn't group just 5 5s as the factorials of 25+ have 6 fives within it. Every even number contributes a 2 so that is where there are plenty of 2s to perform a sort of re-arranging of the prime factorization to get 10^6 within all factorials of 25 or higher. Under 25, there are at most 4 factors that contain a 5: 5, 10, 15, and 20.
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10 的因数是 5 和 2。请注意，5 的第 5 个倍数会将一对 5 带入乘积中，这意味着您不能仅将 5 个 5 分组，因为 25+ 的阶乘中有 6 个 5。每个偶数都贡献一个 2，因此有足够的 2 来执行素因数分解的重新排列，以便在 25 或更高的所有阶乘中获得 10^6。 25岁以下，最多有4个因子包含5：5、10、15和20。
The factors of 10 are 5 and 2. Note that the 5th multiple of 5 will bring a pair of 5s into the product, which means you couldn't group just 5 5s as the factorials of 25+ have 6 fives within it. Every even number contributes a 2 so that is where there are plenty of 2s to perform a sort of re-arranging of the prime factorization to get 10^6 within all factorials of 25 or higher. Under 25, there are at most 4 factors that contain a 5: 5, 10, 15, and 20.