Logic to check even or odd A number exactly divisible by 2 leaving no remainder, is known as even number. Programmatically, if any number modulo divided by 2 equals to 0 then, the number is even otherwise odd. Step by step descriptive logic to check whether a number is even or odd. Input a number from user. Store it in some variable say num . Check if number modulo division equal to 0 or not i.e. if(num % 2 == 0) then the number is even otherwise odd. Important Note: Do not confuse modulo division operator % as percentage operator. There is no percentage operator in C. /** * C program to check even or odd number */ # include <stdio.h> int main ( ) { int num ; /* Input number from user */ printf ( "Enter any number to check even or odd: " ) ; scanf ( "%d" , & num ) ; /* Check if the number is divisible by 2 then it is even */ if ( num % 2 == 0 ) { /* num % 2 is 0 */