C/C++ programming to calculate the number of trailing zeros in the factorial of a number?

Calculating the number of trailing zeros in a factorial number is done by counting the number of 2s and 5s in the factors of the number. Because 2*5 is equal to 10, and 10 is the last zero in the factorial number.

Example

The factorial of 7=5040, and the number of 0s at the end is 1.

According to our logic, 7!=2*3*4*5*6*7, which has 3 2s and 1 5, so the number of 0s at the end is 1.

#include <iostream>
using namespace std;
int main() {
   int n = 45;
   int count = 0;
   for (int i = 5; n / i >= 1; i *= 5)
      count += n / i;
   cout<<"No of trailing 0s in " << n<< "! is " << count;
   return 0;
}

Output

No of trailing 0s in 24! is 10

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