Why we use dpercentage in c from where it come

Answer 1

We call it the modulus-of operator. It returns the remainder of after a division has been carried out.

E.g.

10 / 3 = 3 (with remainder 1)
10 % 3 = 1

Answer 2

sorry but its not percent it is mod.
it will give you the remainder of the operation.
ex. 5%2=1
that is 5 divided by 2: is 2 and the remainder is 1.