# Given a number n, count all multiples of 3 and/or 5 in set {1, 2, 3, … n}

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; ` `} ` |

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## 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. ` |

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## 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. ` |

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## 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. ` |

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## 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 ` `?> ` |

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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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