# Check if a large number is divisible by 5 or not

Given a number, the task is to check if number is divisible by 5. The input number may be large and it may not be possible to store even if we use long long int.

Examples:

Input : n = 56945255 Output : Yes Input : n = 1234567589333150 Output : Yes Input : n = 3635883959606670431112222 Output : No

Since input number may be very large, we cannot use n % 5 to check if a number is divisible by 5 or not, especially in languages like C/C++. The idea is based on following fact.

A number is divisible by 5 if its digits last digit will be 0 or 5 .

**Illustration: **

For example, let us consider 769555 Number formed by last digit is = 5 Since 5 is divisible by 5 , answer is YES.

**How does this work? **

Let us consider 5335, we can write it as 5335 = 5*1000 + 3*100 + 3*10 + 5 The proof is based on below observation: Remainder of 10^{i}divided by 5 is 0 if i greater than or equal to one. Note than 10, 100, 1000, ... etc lead to remainder 0 when divided by 5. So remainder of " 5*1000 + 3*100 + 3*10 + 5" divided by 5 is equivalent to remainder of following : 0 + 0 + 0 + 5 = 5 Since 5 is divisible by 5, answer is yes.

Below is the implementation of above idea.

## C++

`// C++ program to find if a number is ` `// divisible by 5 or not ` `#include<bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// Function to find that number divisble ` `// by 5 or not. The function assumes that ` `// string length is at least one. ` `bool` `isDivisibleBy5(string str) ` `{ ` ` ` `int` `n = str.length(); ` ` ` ` ` `return` `( ((str[n-1]-` `'0'` `) == 0) || ` ` ` `((str[n-1]-` `'0'` `) == 5)); ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `string str = ` `"76955"` `; ` ` ` `isDivisibleBy5(str)? cout << ` `"Yes"` `: ` ` ` `cout << ` `"No "` `; ` ` ` `return` `0; ` `} ` |

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## Java

`// Java program to find if a number is ` `// divisible by 5 or not ` `class` `IsDivisible ` `{ ` ` ` `// Function to find that number divisble ` ` ` `// by 5 or not. The function assumes that ` ` ` `// string length is at least one. ` ` ` `static` `boolean` `isDivisibleBy5(String str) ` ` ` `{ ` ` ` `int` `n = str.length(); ` ` ` ` ` `return` `( ((str.charAt(n-` `1` `)-` `'0'` `) == ` `0` `) || ` ` ` `((str.charAt(n-` `1` `)-` `'0'` `) == ` `5` `)); ` ` ` `} ` ` ` ` ` `// main function ` ` ` `public` `static` `void` `main (String[] args) ` ` ` `{ ` ` ` `String str = ` `"76955"` `; ` ` ` `if` `(isDivisibleBy5(str)) ` ` ` `System.out.println(` `"Yes"` `); ` ` ` `else` ` ` `System.out.println(` `"No"` `); ` ` ` `} ` `} ` |

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## Python

`# Python program to find if a number is ` `# divisible by 5 or not ` ` ` `# Function to find that number divisble ` `# by 5 or not. The function assumes that ` `# string length is at least one. ` `def` `isDivisibleBy5(st) : ` ` ` `n ` `=` `len` `(st) ` ` ` `return` `( (st[n` `-` `1` `] ` `=` `=` `'0'` `) ` `or` ` ` `(st[n` `-` `1` `] ` `=` `=` `'5'` `)) ` ` ` `# Driver code ` `st ` `=` `"76955"` `if` `isDivisibleBy5(st) : ` ` ` `print` `"Yes"` `else` `: ` ` ` `print` `"No "` ` ` `# This code is contributed by Nikita Tiwari. ` |

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## C#

`// C# program to find if a number is ` `// C# program to find if a number ` `// is divisible by 5 or not. ` `using` `System; ` ` ` `class` `IsDivisible ` `{ ` ` ` `// Function to find that number divisble ` ` ` `// by 5 or not. The function assumes that ` ` ` `// string length is at least one. ` ` ` `static` `bool` `isDivisibleBy5(String str) ` ` ` `{ ` ` ` `int` `n = str.Length; ` ` ` ` ` `return` `(((str[n - 1] - ` `'0'` `) == 0) || ` ` ` `((str[n - 1] - ` `'0'` `) == 5)); ` ` ` `} ` ` ` ` ` `// Driver Code ` ` ` `public` `static` `void` `Main () ` ` ` `{ ` ` ` `String str = ` `"76955"` `; ` ` ` `if` `(isDivisibleBy5(str)) ` ` ` `Console.Write(` `"Yes"` `); ` ` ` `else` ` ` `Console.Write(` `"No"` `); ` ` ` `} ` `} ` ` ` `// This code is cotributed by Nitin Mittal. ` |

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## PHP

`<?php ` `// PHP program to find if a number ` `// is divisible by 5 or not ` ` ` `// Function to find that number divisble ` `// by 5 or not. The function assumes that ` `// string length is at least one. ` `function` `isDivisibleBy5(` `$str` `) ` `{ ` ` ` `$n` `= ` `strlen` `(` `$str` `); ` ` ` ` ` `return` `( ((` `$str` `[` `$n` `-1]-` `'0'` `) == 0) || ` ` ` `((` `$str` `[` `$n` `-1]-` `'0'` `) == 5)); ` `} ` ` ` `// Driver code ` `$str` `= ` `"76955"` `; ` `$x` `= isDivisibleBy5(` `$str` `) ? ` `"Yes"` `: ` `"No"` `; ` `echo` `(` `$x` `); ` ` ` `// This code is contributed by Ajit. ` `?> ` |

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Output:

Yes

This article is contributed by DANISH_RAZA . If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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