s.f.

Significant Figures Counter

Arithmetic & NumbersFreeStep by step

Significant figures are the digits in a number that carry meaningful precision. Leading zeros never count, zeros between other digits always count, and trailing zeros count only when there is a decimal point. This counter applies those rules to the number exactly as you typed it and explains each one.

Type it exactly as written; trailing zeros matter.
Try:

How to use the significant figures counter

  1. Type the number exactly as written, including any zeros.
  2. Press Calculate.
  3. Read the count and the rule behind each digit.

Formula

0.004050‾⇒4 s.f.0.00\underline{4050} \Rightarrow 4 \text{ s.f.}

Worked example: 0.004050

  • Number (as written): 0.004050

✓ Answer checked

4 significant figures

Step-by-step working (4 steps)

  1. Leading zeros never count

    Zeros before the first non-zero digit only show the place value.

    000 not counted\text{000} \text{ not counted}

  2. Zeros between digits count

    Any zero between two non-zero digits is significant.

  3. Trailing zeros

    There is a decimal point, so trailing zeros are significant (they show precision).

  4. Count

    Count from the first significant digit to the last.

    44
How this was checked
  • ✓ Counting from the first non-zero digit to the last significant digit gives the same answer.

Frequently asked questions

How many significant figures does 0.004050 have?

Four: 4, 0, 5 and the final 0. The leading zeros do not count.

How many significant figures does 1200 have?

Two, strictly, because trailing zeros without a decimal point are place holders. Writing 1200. or 1.200 × 10³ shows four.

Do zeros in the middle count?

Yes. In 1005 all four digits are significant.

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