Numbers

Rounding Calculator

Round any number to a specified number of decimal places or significant figures. The calculator identifies the rounding digit, checks the next digit, and shows the decision at every step.

Rounded to 2 d.p.

3.14

How it works

  1. Identify the 2nd decimal place

    We are rounding to 2 decimal places. Look at the 3rd decimal place to decide whether to round up or down.

  2. The deciding digit is 1

    3.1416

    The digit in the 3th decimal place is 1. Since it is less than 5, round down (keep the digit as-is).

  3. Result

    3.141593.143.14159 \approx 3.14

    3.14159 rounded to 2 decimal places is 3.14.

    Result:3.14

The formula

Round to n d.p. or s.f.: look at digit (n+1)\text{Round to } n \text{ d.p. or s.f.: look at digit } (n+1)
nnNumber of decimal places or significant figures
Digit(n+1)Digit (n+1)If ≥ 5, round up. If < 5, round down.

Example substitution

3.14159 to 2 d.p.=3.143.14159 \text{ to 2 d.p.} = 3.14

Keep 2 decimal places. The 3rd digit is 1 (< 5), so round down: 3.14.

Worked examples

Round 3.14159 to 2 decimal places.

  1. 1
    Keep 2 d.p.: 3.14...
  2. 2
    3rd digit: 1 < 5, round down
Answer: 3.14

Round 2.785 to 2 decimal places.

  1. 1
    Keep 2 d.p.: 2.78...
  2. 2
    3rd digit: 5 ≥ 5, round up
Answer: 2.79

Round 4567 to 2 significant figures.

  1. 1
    First 2 s.f.: 45...
  2. 2
    Next digit: 6 ≥ 5, round up
  3. 3
    Fill with zeros: 4600
Answer: 4600

Frequently asked questions

How do you round to 2 decimal places?+

Look at the third decimal place. If it is 5 or more, round up the second decimal place; if less than 5, leave it unchanged.

What are significant figures?+

Significant figures are the meaningful digits in a number, starting from the first non-zero digit. E.g., 0.00450 has 3 significant figures.

How do you round 3.456 to 2 decimal places?+

3.456 rounded to 2 d.p. is 3.46 — the third decimal (6) is ≥ 5, so we round up.

How do you round to 3 significant figures?+

Find the third significant figure, look at the next digit, and apply the rounding rule. E.g., 45,678 to 3 s.f. = 45,700.

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