Standard form (scientific notation)
a × 10n where 1 ≤ a < 10. Year 9 introduces; GCSE consolidates.
Standard form writes large or tiny numbers compactly. Speed of light: 3 × 108 m/s. Mass of an electron: 9.11 × 10−31 kg.
Worked examples
3,400,000 = 3.4 × 106.
0.000045 = 4.5 × 10−5.
(2 × 103) × (3 × 104) = 6 × 107.
Frequently asked questions
Why must a be 1 to 10?
Uniqueness. 34 × 105 and 3.4 × 106 are equal but only the second is ‘in standard form’.
On a calculator?
Casio fx-83/85 displays 3.4×106 as 3.4E6 or 3.4×10^6. Mode > SciENG to set.