Round it at any digit
"To the nearest hundred" names a place on the number, not a rule to apply. Slide along the digits: one number gives a different right answer at every place you stop.
Or click a digit of the top number to jump straight to it.
1825 to the nearest 10 1830
- Rounding at
- Tens
The number
How many digits
Ready to try some? Rounding numbers worksheets
Where it usually goes wrong
Rounding is done as a chant — five and above, round up — without noticing that the answer depends entirely on which place you are rounding at. 1825 is 1830 to the nearest ten and 1800 to the nearest hundred, and both are right. Rounding twice is where it does real damage: 1849 to the nearest ten is 1850, and rounding that again gives 1900 for a number that was never near it.
Try this
- Round 1825 at the tens, then at the hundreds, then at the thousands. Three different right answers.
- Click the digits along the top to jump between places, and watch which digit is doing the deciding each time.
- Switch the number to one with decimals and round at the hundredths. It is the same move in the other direction.
Where this goes next
Every estimate, every measurement written to a sensible number of figures, and every price rounded to the penny is this, and getting it wrong quietly is the most common numerical error there is.