How many significant figures in 2?
2 has 1 significant figure. A counted or defined number, such as 2 coins, is exact and has unlimited significant figures. A measured 2 has 1.
Significant figures
Non-zero digit. Every non-zero digit is significant.Zero between digits. A zero between two non-zero digits is significant.Leading zero. Leading zeros only fix the decimal point, so they are not significant.Trailing zero after the point. Trailing zeros in a number with a decimal point are significant.Trailing zero, no point. Trailing zeros in a number without a decimal point are not counted. Write 1.00 × 10² to make them count.Digit of a in a × 10ⁿ. In a × 10ⁿ every digit of a is significant, including its zeros. Counted and defined numbers, such as 3 coins or 100 cm in a metre, are exact and have unlimited significant figures.
Tap a digit to see why it counts.
1significant figure
Scientific notation2 × 100
Round to
2→2
Nothing is dropped.
Add, subtract, multiply, divide
Add or subtract. The answer keeps as many decimal places as the number that has the fewest. Multiply or divide. The answer keeps as many significant figures as the number that has the fewest. The rounding is done once, on the exact result.
- 4.2374 significant figures
- 2.513 significant figures
Exact result1.68804780876
Multiply or divide: keep the fewest significant figures.
Reported1.693 significant figures
Digit by digit
- 2
Non-zero digit: countsEvery non-zero digit is significant.
2 × 10⁰
Nearby numbers
Rounding a value? See 2.745 to 3 significant figures.
2: quick answers
How many significant figures does 2 have?
2 has 1 significant figure. In 2, every digit is non-zero, so every digit counts. A counted or defined number, such as 2 coins, is exact and has unlimited significant figures. A measured 2 has 1.
How do I write 2 in scientific notation?
2 = 2 × 10⁰, with 1 significant figure in the mantissa.
Can a number have fewer than one significant figure?
No. 2 already has the fewest, 1 significant figure.