The product a x a x a x a can be written as a4, where 4 is called the exponent of a or power to which a is raised. In this notation, a is frequent called the base.
a4 = a. a. a. a
53 = 5. 5. 5
(a + b)5 = (a+b) . (a+b) . (a+b) . (a+b). (a+b)
While an exponent is not written, it is supposed to be 1. For example, a1 = a. An exponent applies only to the quantity immediately to the left and below it. For example, in 3 + (-2)3 the base is -2, but in 3 - 23 the base is 2.