What is scientific notation?
Scientific notation writes very large or very small numbers as a number between 1 and 10 multiplied by a power of 10. Instead of 300,000,000 meters per second for the speed of light, scientists write 3 × 10⁸ m/s. Instead of 0.000000001 meters, they write 1 × 10⁻⁹ m.
a × 10ⁿ, where 1 ≤ |a| < 10 and n is a whole number
Converting to scientific notation
- Move the decimal point so one non-zero digit is to its left.
- Count how many places you moved it.
- If you moved it left, the exponent is positive. If you moved it right, it is negative.
- 93,000,000 → 9.3 × 10⁷ (moved 7 places left)
- 0.00045 → 4.5 × 10⁻⁴ (moved 4 places right)
Converting back to a normal number
Move the decimal point by the exponent: right for a positive exponent, left for a negative one, filling gaps with zeros. 2.7 × 10³ = 2,700 and 2.7 × 10⁻³ = 0.0027.
Where you will see it
- Chemistry: Avogadro's number is about 6.022 × 10²³.
- Astronomy: the Sun is about 1.5 × 10⁸ km from Earth.
- Biology: a typical bacterium is around 1 × 10⁻⁶ meters long.
- Computing: spreadsheets show huge numbers as 1.2E+12.
Last reviewed October 2026.