What Is Scientific Notation?
Scientific notation is a compact way to write very large or very small numbers. A number is in scientific notation when it is written as:
a × 10ⁿ
where 1 ≤ |a| < 10 (the coefficient has exactly one non-zero digit before the decimal point) and n is any integer.
Examples:
- 93,000,000 = 9.3 × 10⁷
- 0.000042 = 4.2 × 10⁻⁵
- −5,600 = −5.6 × 10³
Scientific notation is standard in physics, chemistry, astronomy, and engineering — anywhere numbers span many orders of magnitude.
How to Convert to Scientific Notation
- Move the decimal point until exactly one non-zero digit sits to the left of it.
- Count the moves — that count becomes the exponent.
- Moved left (number got smaller) → exponent is positive
- Moved right (number got larger) → exponent is negative
- Write the result as coefficient × 10^exponent.
Example — large number: 93,000,000 → move decimal 7 places left → 9.3 × 10⁷
Example — small number: 0.000042 → move decimal 5 places right → 4.2 × 10⁻⁵
The Four Notation Formats
Scientific Notation
The standard form: coefficient between 1 and 10, multiplied by a power of 10.
Example: 9.3 × 10⁷
E-Notation
Compact shorthand used in programming languages, spreadsheets, and scientific calculators. The letter E replaces × 10^ and the sign on the exponent is always explicit.
Example: 9.3E+7
Engineering Notation
Like scientific notation, but the exponent is always a multiple of 3. This aligns with SI unit prefixes: 10⁻⁹ = nano, 10⁻⁶ = micro, 10⁻³ = milli, 10³ = kilo, 10⁶ = mega, 10⁹ = giga. The coefficient ranges between 1 and 1000.
Example: 93 × 10⁶ (read as 93 megahertz rather than 9.3 × 10⁷ Hz)
Decimal
The fully expanded number with thousands separators where applicable.
Example: 93,000,000
Arithmetic in Scientific Notation
Multiplication
Multiply the coefficients and add the exponents:
(a × 10ᵐ) × (b × 10ⁿ) = (a · b) × 10^(m + n)
Example: (3 × 10⁴) × (2 × 10³) = 6 × 10⁷
Division
Divide the coefficients and subtract the exponents:
(a × 10ᵐ) ÷ (b × 10ⁿ) = (a ÷ b) × 10^(m − n)
Example: (8 × 10⁶) ÷ (2 × 10²) = 4 × 10⁴
Addition and Subtraction
Convert both numbers to the same exponent, then add or subtract the coefficients:
(3 × 10⁵) + (5 × 10⁴) = (3 × 10⁵) + (0.5 × 10⁵) = 3.5 × 10⁵
If the resulting coefficient falls outside 1–10, renormalize: 12 × 10⁴ = 1.2 × 10⁵.
Sources
- BIPM. The International System of Units (SI), 9th edition. Bureau International des Poids et Mesures. 2019.
- NIST. Guide for the Use of the International System of Units (SP 811). National Institute of Standards and Technology. 2008.