Brainlag Plus
Brainlag PlusEstimating and checking
Round to 1 significant figure, estimate a calculation and say whether it is too big or too small, and use a fact you are given to find related answers.
Estimating a calculation
Round every number to 1 significant figure, then work it out. For a square root, use the nearest square number instead.
- (6.12 × 38.4) ÷ 0.48
- 6.12 ≈ 6, 38.4 ≈ 40, 0.48 ≈ 0.5
- 6 × 40 = 240
- 240 ÷ 0.5 = 480
- √47.3 × 21.6
- 47.3 is close to 49, so √47.3 ≈ 7
- 21.6 ≈ 20
- 7 × 20 = 140
The rest of this lesson and its 8 practice questions are in Plus.
Screen 1 of 4, free to read.
- 8 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards