Numford
Significant figures

How many significant figures in 3.14159?

3.14159 has 6 significant figures. This is π to 6 significant figures. π itself is exact, so its figures are as many as you choose to keep.

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.

6significant figures
Scientific notation3.14159 × 100

Round to

6
significant figures

3.141593.14159

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
The rule used

Digit by digit

  • 314159

    Non-zero digit: countsEvery non-zero digit is significant.

Scientific notation

3.14159 × 10⁰

  • Rounded to 4 significant figures3.142
  • Rounded to 5 significant figures3.1416
Related

Nearby numbers

Rounding a value? See 2.745 to 3 significant figures.

Questions

3.14159: quick answers

How many significant figures does 3.14159 have?

3.14159 has 6 significant figures. In 3.14159, every digit is non-zero, so every digit counts. This is π to 6 significant figures. π itself is exact, so its figures are as many as you choose to keep.

How do I write 3.14159 in scientific notation?

3.14159 = 3.14159 × 10⁰, with 6 significant figures in the mantissa.

What is 3.14159 rounded to 5 significant figures?

3.14159 rounded to 5 significant figures is 3.1416. The dropped part 9 is more than half, so the last kept digit 5 goes up by one.

Count your own number Open error analysis