There are several math expression which are showed in the example below.Code Structure
var num1 = 10; num1++; // returns 10, 11, 12 etc var num2 = 20; num2--; // returns 20, 19, 18 etc var num3 = 10; ++num3; // returns 11, 12, 13 etc var num4 = 20; --num4; // returns 19, 18, 17 etc