What is rounding off?
Rounding off makes a number simpler by changing it to the nearest ten, hundred, thousand, and so on. We use it to estimate and to report numbers neatly.
The rounding rule
First, find the place you are rounding to. Then look at the digit just after it. If that digit is 5 or more, round up (add 1 to the rounding place). If it is 4 or less, round down (keep the rounding place the same). Every digit after the rounding place then becomes 0.
Key idea
0, 1, 2, 3, 4 → round down. 5, 6, 7, 8, 9 → round up.
Worked example
Round 3 476 to the nearest thousand. The thousands digit is 3 and the next digit is 4. Since 4 is less than 5, we round down: 3 476 → 3 000.
Remember
- Check the digit to the right of the rounding place.
- 5 or more rounds up; 4 or less rounds down.
- All digits after the rounding place become 0.