# Using an index or power

Here is a number written in index form:

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

$$2^4$$ is a short way of writing $$2 \times 2 \times 2 \times 2$$.

The power or index shows how many times a number has been multiplied by itself.

### Using algebra

$$a^3$$ (read as ‘$$a$$ cubed’) is a short way of writing $$a \times a \times a$$.

$$a$$ has been multiplied by itself three times.

Similarly, $$a^2$$ (read as '$$a$$ squared’) is a short way of writing $$a \times a$$.

$$a$$ has been multiplied by itself.

$$a^1$$ (read as '$$a$$ to the power of 1') is written as simply $$a$$.