3³ ('3 to the power of 3') and 5² (5 'to the power' of 2) are example of numbers in index form.
3³ = 3×3×3
2¹ = 2
2² = 2×2
2³ = 2×2×2
etc...

The ² and ³ are known as indices. Indices are useful (for example they allow us to represent numbers in standard form) and have a number of properties. These properties only hold, however, when the same number is being raised to a certain power. For example, we cannot easily work out what 2³×5² is, whereas we can simplify 3²×3³ .

Copyright © Matthew Pinkney 2003