Rounding
Look at the digit to the right of where you are rounding. If it is 5 or more, round up. Otherwise, round down.
Rounding replaces a number with a simpler one that is close in value. We round to a given place value (nearest 10, 100, 1000) or to a certain number of decimal places (d.p.) or significant figures (s.f.).
The rule is always the same. Find the digit in the position you are rounding to, then look at the next digit to its right. If that digit is 5, 6, 7, 8, or 9 the rounding digit goes up by one. If it is 0, 1, 2, 3, or 4 the rounding digit stays the same.
On a number line, the value always falls between two "round" numbers. The halfway point decides which way it goes.
Choose an example to see where the value sits on the number line and which boundary it rounds to.
Watch it work
Question: Round 4 372 to the nearest 100.
Step 1: Identify the hundreds digit. In 4 372 the hundreds digit is 3 (giving 4 300).
Step 2: Look at the next digit to the right. That is the tens digit, 7.
Step 3: Since , we round the hundreds digit up: 3 becomes 4.
Answer: 4 372 rounded to the nearest 100 is 4 400.
Have a go
Q1. Round 857 to the nearest 10.
The tens digit is 5. Look right: the units digit is 7. Since , round up.
860.
Q2. Round 6 432 to the nearest 1 000.
The thousands digit is 6. Look right: the hundreds digit is 4. Since , round down.
6 000.
Q3. Round 3.456 to 1 decimal place.
The first decimal digit is 4. Look right: the next digit is 5. Since , round up.
3.5.
Q4. Round 0.0847 to 2 significant figures.
The first significant figure is 8 (ignore leading zeros). The second is 4. Look right: the next digit is 7. Since , round up.
0.085.