# Number of 1’s in bit representation of a number

**Objective**: Write an algorithm to count the number of 1’s in the bit representation in given number.

**Example**:

Number: 6 Output: 2 ( 1 1 0) Number: 11 Output: 3 ( 1 0 1 1)

** Approach:**

**Method 1:**

- While number > 0
- Keep doing the
*number & 1*, increment count if result is 1 - Do the right shift

**Method 2:**

- While number > 0
- Keep doing the
*number MOD 2*, increment count if result is 1 - Divide the number by 2.

**Method 3: Brian Kernighan’s Algorithm**

- While number > 0
- Increment the count.
- Keep doing the
*number & number –1.*

**Example**:

n = 6 count = 1 Bit representation: 1 1 0 n-1 = 5 => 1 0 1 n = n & n-1 => 1 1 0 & 1 0 1 => 1 0 0 Now n = 4 Count = 2 Bit representation: 1 0 0 n-1 = 3 n = n & n-1 => 1 0 0 & 0 1 1 => 0

**Complete Code:**

**Output**:

Number of 1's in the binary representation of 6 is: 2