Estimation and Checking
Ages 8–13Difficulty adapts to you
Estimation and Checking
Estimation gives a quick approximate answer before you calculate. Afterwards, inverse operations and a second method help you detect mistakes.
Your goals
- ✓You can estimate answers and use inverse operations to check calculations.
- ✓You can use estimate, inverse operation correctly.
- ✓You can compare your exact answer with your estimate.
Words to know
- estimate:
- A sensible answer close to the exact value.
- inverse operation:
- An operation that can undo another operation.
Examples
- 1398 + 205 is about 400 + 200 = 600.
- 2If 84 ÷ 7 = 12, check with 12 × 7 = 84.
Check these
- • Do not present an estimate as though it were exact.
- • Keep every number, symbol, label, and unit in its correct place.
- • Show enough working to check how you reached your answer.
Helpful habits
- • Read the whole question before choosing what to do.
- • Show one clear step at a time and check each step.
- • If you are stuck, draw a model, try smaller numbers, or revisit the example.
Now try your own
Create your own estimation and checking example, solve it, and explain how you checked it.
Professor Wise Owl
Wisdom & Understanding“Understanding "why" is more powerful than memorising "how".”