The index of a number says how many times to use the number in a multiplication.

It is written as a small number to the right and above the base number.

In this example the index is **2**: 8^{2} = 8 × 8 = 64

(It says to use 8 **2 times** in a multiplication)

Another example: 5^{3} = 5 × 5 × 5 = 125

The plural of index is indices.

(Other names for index are **exponent** or **power**.)