**Prerequisite : **Compute modulus division by a power-of-2-number

Now as you know for getting n modulus 2^{k}, we just need to return k bits(from LSB) in binary representation of n. In Java, you can use Wrapper class *toBinaryString()* method to get binary string representation of a number and getting substring from (str.length()-k) to end. And then by using *Integer.parseInt()*, you can convert this binary substring to number which is the remainder. Below is the Java program to demonstrate the same.

`// Java program to Compute modulus` `// division by a power-of-2-number` ` ` `class` `Test` `{` ` ` `// Driver method` ` ` `public` `static` `void` `main(String[] args) ` ` ` `{` ` ` `int` `num = ` `15` `;` ` ` ` ` `int` `two_power1 = ` `1` `;` ` ` `int` `two_power2 = ` `2` `;` ` ` `int` `two_power3 = ` `3` `;` ` ` ` ` `String binary = Integer.toBinaryString(num);` ` ` `int` `len = binary.length();` ` ` ` ` `String rem1 = binary.substring(len-two_power1);` ` ` `String rem2 = binary.substring(len-two_power2);` ` ` `String rem3 = binary.substring(len-two_power3);` ` ` ` ` `int` `reme1 = Integer.parseInt(rem1, ` `2` `);` ` ` `int` `reme2 = Integer.parseInt(rem2, ` `2` `);` ` ` `int` `reme3 = Integer.parseInt(rem3, ` `2` `);` ` ` ` ` `System.out.println(num + ` `"%"` `+ ` `"2^("` `+ two_power1 + ` `") = "` `+ reme1);` ` ` `System.out.println(num + ` `"%"` `+ ` `"2^("` `+ two_power2 + ` `") = "` `+ reme2);` ` ` `System.out.println(num + ` `"%"` `+ ` `"2^("` `+ two_power3 + ` `") = "` `+ reme3);` ` ` `}` `}` |

Output:

15%2^(1) = 1 15%2^(2) = 3 15%2^(3) = 7

This article is contributed by **Gaurav Miglani**. 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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