Real numbers are the set of all numbers
2. Integers are all whole numbers, they can be positive, negative or zero
3. Natural numbers are the set of all positive integers
4. A rational number is a number that can be written as a fraction in its simplest form
5. A factor is a number that divides into another number exactly
6. A multiple is a number that is in the times table of another number
7. A prime number is a number which has exactly two factors, itself and 1
8. A square number is the number derived from multiplying a number by itself
9. A cube number is the number derived from multiplying a number by itself twice
10. An index (indices plural) is a way of writing a string of multiplications of the same number neatly
11. The reciprocal of a number is the result of dividing 1 by that number
12. An irrational number is a number that cannot be written in the form , where and are whole numbers (or integers)
13. Negative numbers are any number less than zero