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Problem 20


Problem 20


Factorial digit sum

n! means n × (n − 1) × … × 3 × 2 × 1

For example, 10! = 10 × 9 × … × 3 × 2 × 1 = 3628800, and the sum of the digits in the number 10! is 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27.

Find the sum of the digits in the number 100!


阶乘数字和

n! 的意思是 n × (n − 1) × … × 3 × 2 × 1

例如,10! = 10 × 9 × … × 3 × 2 × 1 = 3628800,所以10!的各位数字和是 3 + 6 + 2 + 8 + 8 + 0 + 0 = 27。

求出100!的各位数字和。