大象传媒

Laws of indices - EdexcelUsing an index or power

Indices are used to show numbers that have been multiplied by themselves. They can be used instead of the roots such as the square root. The rules make complex calculations that involve powers easier.

Part of MathsNumber

Using an index or power

An index, or a power, is the small floating number that goes next to a number or letter. The plural of index is indices.

Indices show how many times a number or letter has been multiplied by itself.

Here is a number written in index form:

Example of how to write numbers in index form. Base number shown as 2 and the power or index number shown as 4.

2 is the base number and 4 is the index or power.

24 is a short way of writing \(2 \times 2 \times 2 \times 2\).

\(a^2\) (read as '\(a\) squared鈥) is a short way of writing \(a \times a\). \(a\) has been multiplied by itself.

a^3 (read as 鈥a cubed鈥) is a short way of writing a \times a \times a. a has been multiplied by itself three times.

Example of how to write letters in algebraic form. Base letter shown as A and the power or index number shown as 3.

\(a^4\) (read as 鈥榎(a\) to the power of 4') is a short way of writing \(a \times a \times a \times a\). \(a\) has been multiplied by itself four times, and so on.