Maths trick
Estimating
Round the numbers to work out roughly what the answer should be.
Ages 8–13
Worked example
Tap through the steps. Each step can be read aloud.
Step 1 of 4
Is 49 × 21 about 100, 1000 or 10 000? Round each number first.
Quick practice
Five fresh questions, marked straight away. Use the trick!
Round the numbers to work out roughly what the answer should be.
More tricks
Column addition
Line up the digits by place value, add from the ones, and carry when a column makes 10 or more.
Column subtraction
Subtract from the ones; when the top digit is too small, exchange 1 from the next column.