One of the uses of Modulus is to detect if a number is even or odd.
If a number is evenly divisible by 2 leaving a remainder of zero then
the number is even.
If the number is not evenly divisible by 2 and leaves a remainder of 1 then it is an
odd number.
For example when dividing numbers say
8 and 2
results in a remainer of
0
So 8 is an even number.
While dividing numbers
7 and 2,
results in a remainder of
1
So 7 is an odd number.
Example
Find all student ids which are even.