Significant Figures

Count significant figures, round to them and write numbers in scientific notation.

Runs entirely in your browser. Nothing you type or paste is sent anywhere.

Count significant figures

Number

Type it exactly as written, zeros included. Scientific notation like 6.02e23 or 6.02 × 10^23 works too.

Significant figures in 0.004050

4significant figures

Round tosignificant figures

Rounded

0.0041

Scientific notation: 4.1 × 10⁻³
Engineering notation: 4.1 × 10⁻³; The power of ten is always a multiple of 3, like kilo (10³) or milli (10⁻³).
E notation: 4.1E-3; How calculators and spreadsheets write it.

Rounding looks at the next digit: 5 or more rounds up, 4 or less rounds down.

First number

Second number

2.5 × 3.42 =8.6

2.5 has 2 significant figures and 3.42 has 3 significant figures. For × and ÷ the answer keeps the fewest: 2.
Exact answer: 8.55, rounded: 8.6 (8.6 × 10⁰)

1.
Non-zero digits always count.
4.56 has 3
Applies
2.
Zeros between non-zero digits count.
1002 has 4
Applies
3.
Zeros at the start never count; they only show where the decimal point goes.
0.0045 has 2
Applies
4.
Zeros at the end count when there is a decimal point.
2.50 and 100.0 have 3 and 4
Applies
5.
Zeros at the end of a whole number are unclear without a decimal point.
1500 has 2, 3 or 4

The power of ten in scientific notation never changes the count: 4.50 × 10⁻³ has 3 significant figures.

All 118 elements with atomic mass, electron configuration and group; search, filter and compare.

Molar mass and mass percentages from a chemical formula, including brackets and hydrates.

Enter any three of displacement, initial and final velocity, acceleration and time to get the other two, with working.