# 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 ` `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

 ` `

Output:

```3
7```

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Improved By : Sam007, nitin mittal, vt_m

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