Numbers

• Maths Grids – featuring multiplication grids, and addition and subtracation grids.

• Number Sets – natural numbers, whole numbers, integers, rational numbers, irrational numbers, real numbers, complex numbers. Also why 0.9 recurring is the same as 1.

• Prime Numbers – divisible only by themselves and 1.

• Complex Numbers – real and imaginary parts in one number. Square roots of negative numbers.

• Messing With Infinity – best left well alone.

• Prefixes – how measurement units are made easier to use with really big and really small numbers. This page lists the 20 prefixes that are used by the Système International, plus an example of converting dimensions given in mm into a volume in litres.