Given a number n, count all multiples of 3 and/or 5 in set of numbers from 1 to n.

Examples:

Input: n = 6 Output: 3 There are three multiples of 3 and/or 5 in {1, 2, 3, 4, 5, 6} Input: n = 16 Output: 7 There are two multiples of 7 and/or 5 in {1, 2, .. 16} The multiples are 3, 5, 6, 9, 10, 12, 15

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The value of n/3 gives us number of multiples of 3, the value of n/5 gives us number of multiples of 5. But the important point is there are may be some common multiples which are multiples of both 3 and 5. We can get such multiples by using n/15. Following is the program to find count of multiples.

## C++

`// C++ program to find count of multiples of 3 and 5 in {1, 2, 3, ..n}` `#include <iostream>` `using` `namespace` `std;` ` ` `unsigned countOfMultiples(unsigned n)` `{` ` ` `// Add multiples of 3 and 5. Since common multples are` ` ` `// counted twice in n/3 + n/15, subtract common multiples` ` ` `return` `(n/3 + n/5 - n/15);` `}` ` ` `// Driver program to test above function` `int` `main()` `{` ` ` `cout << countOfMultiples(6) << endl;` ` ` `cout << countOfMultiples(16) << endl;` ` ` `return` `0;` `}` |

## Java

`// Java program to find count of multiples` `// of 3 and 5 in {1, 2, 3, ..n}` `import` `java .io.*;` `class` `GFG {` ` ` ` ` `static` `long` `countOfMultiples(` `long` `n)` ` ` `{` ` ` ` ` `// Add multiples of 3 and 5. ` ` ` `// Since common multples are` ` ` `// counted twice in n/3 + n/15, ` ` ` `// subtract common multiples` ` ` `return` `(n/` `3` `+ n/` `5` `- n/` `15` `);` ` ` `}` ` ` ` ` `// Driver Code` ` ` `static` `public` `void` `main (String[] args)` ` ` `{` ` ` `System.out.println(countOfMultiples(` `6` `));` ` ` `System.out.println(countOfMultiples(` `16` `));` ` ` `}` `}` ` ` `// This code is contributed by anuj_67.` |

## Python3

`# python program to find count` `# of multiples of 3 and 5 in ` `# {1, 2, 3, ..n}` ` ` `def` `countOfMultiples(n):` ` ` `# Add multiples of 3 and 5.` ` ` `# Since common multples are` ` ` `# counted twice in n/3 + n/15,` ` ` `# subtract common multiples` ` ` `return` `(` `int` `(n` `/` `3` `) ` `+` `int` `(n` `/` `5` `) ` `-` `int` `(n` `/` `15` `));` ` ` ` ` `# Driver program to test` `# above function` `print` `(countOfMultiples(` `6` `))` `print` `(countOfMultiples(` `16` `))` ` ` `# This code is contributed by Sam007.` |

## C#

`// C# program to find count of multiples` `// of 3 and 5 in {1, 2, 3, ..n}` `using` `System;` ` ` `public` `class` `GFG {` ` ` ` ` `static` `uint` `countOfMultiples(` `uint` `n)` ` ` `{` ` ` `// Add multiples of 3 and 5. ` ` ` `// Since common multples are` ` ` `// counted twice in n/3 + n/15, ` ` ` `// subtract common multiples` ` ` `return` `(n/3 + n/5 - n/15);` ` ` `}` ` ` ` ` `// Driver program to test above` ` ` `// function` ` ` `static` `public` `void` `Main ()` ` ` `{` ` ` `Console.WriteLine(countOfMultiples(6));` ` ` ` ` `Console.WriteLine(countOfMultiples(16)) ;` ` ` `}` `}` ` ` `// This code is contributed by anuj_67.` |

## PHP

`<?php` `// PHP program to find count of ` `// multiples of 3 and 5 in ` `// {1, 2, 3, ..n}` ` ` `function` `countOfMultiples(` `$n` `)` `{` ` ` ` ` `// Add multiples of 3 and 5. ` ` ` `// Since common multples are` ` ` `// counted twice in n/3 + n/15,` ` ` `// subtract common multiples` ` ` `return` `floor` `(` `floor` `(` `$n` `/ 3) + ` ` ` `floor` `(` `$n` `/ 5) - ` ` ` `floor` `(` `$n` `/ 15));` `}` ` ` `// Driver Code` `echo` `countOfMultiples(6),` `"\n"` `;` `echo` `countOfMultiples(16);` ` ` `// This code is contributed by nitin mittal` `?>` |

Output:

3 7

This article is contributed by **Asif**. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

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