What is estimation?
Estimation means making a good guess that is close, without counting every one. It helps us answer quickly.
Key idea
To round to the nearest ten: numbers 1-4 go down, numbers 5-9 go up. So 8 rounds up to 10.
Sensible guesses
A good estimate is close to the real amount, not silly. A few sweets is about 5, not 500.
Worked example
Round 12 to the nearest ten. The ones digit is 2 (small), so we go down to 10.
Remember
- An estimate is close, not exact.
- 5 or more rounds up; 4 or less rounds down.