What use are variables, especially numeric variables, if you cannot do some math with them?
Here are some common functions as an example:
int a = 1 ; int b = 2 ; int c = 0 ; math c = a + 5 ; /* sum */ math c = a - b ; /* subtract */ math c = a * b ; /* multiply */ math c = a / b ; /* divide */ math c = a mod b ; /* modulus */
Notice the keyword math.