C# Program to Count trailing zeroes in factorial of a number

Given an integer n, write a function that returns count of trailing zeroes in n!.

**Examples :**

Input: n = 5 Output: 1 Factorial of 5 is 120 which has one trailing 0. Input: n = 20 Output: 4 Factorial of 20 is 2432902008176640000 which has 4 trailing zeroes. Input: n = 100 Output: 24

Trailing 0s in n! = Count of 5s in prime factors of n! = floor(n/5) + floor(n/25) + floor(n/125) + ....

## C#

`// C# program to count ` `// trailing 0s in n! ` `using` `System; ` ` ` `class` `GFG { ` ` ` ` ` `// Function to return trailing ` ` ` `// 0s in factorial of n ` ` ` `static` `int` `findTrailingZeros(` `int` `n) ` ` ` `{ ` ` ` `// Initialize result ` ` ` `int` `count = 0; ` ` ` ` ` `// Keep dividing n by powers ` ` ` `// of 5 and update count ` ` ` `for` `(` `int` `i = 5; n / i >= 1; i *= 5) ` ` ` `count += n / i; ` ` ` ` ` `return` `count; ` ` ` `} ` ` ` ` ` `// Driver Code ` ` ` `public` `static` `void` `Main() ` ` ` `{ ` ` ` `int` `n = 100; ` ` ` `Console.WriteLine(` `"Count of trailing 0s in "` ` ` `+ n + ` `"! is "` `+ findTrailingZeros(n)); ` ` ` `} ` `} ` ` ` `// This code is contributed by vt_m ` |

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**Output:**

Count of trailing 0s in 100! is 24

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