A person's ability to use and understand numbers:

· knowing their relative values,

· how to use them to make decisions,

· using them in flexible ways when adding, subtracting, multiplying or dividing

· developing strategies when counting, measuring or estimating.

Examples:

• knowing that a million is very very much smaller than a billion.

• calculate 102 × 5 by thinking: "100 lots of 5 plus 2 lots of 5, which is 500 plus 10, which is 510"

• quickly estimating a supermarket receipt by rounding each number before adding.