Find remainder without using modulo operator

Objective: Write Given two integers ‘number’ and ‘divisor’, Write an algorithm to find the remainder if ‘number’ is divided by ‘divisor’.

Condition: You are not allowed to use modulo or % operator.

Example:

num = 10, divisor = 4
remainder = 2

num = 11, divisor = 2
remainder = 1

This is fun puzzle which is asked in the interview.

Approach:

1. This problem will become very trivial if use of modulo or % operator is allowed.

2. Idea is Keep subtracting the divisor from number till number>=divisor.

3. Once the step above is done, remaining value of number will be the remainder.

Example:

number = 10, divisor = 4
number = number – divisor => 10 – 4 = 6
number = number – divisor => 6 – 4 = 2
remainder = 2

Code:

Output:

Number: 10, divisor: 4. remainder: 2

ashot madatyan says:
March 11, 2018 at 2:59 am
Continuously subtracting is not such an effective way to go. Instead, we can do it like this:
mul = int(number/divisor);
remainder = number – mul * divisor;