The 11+ rewards speed almost as much as accuracy. These five mental tricks shave seconds off common operations.
1. Round and adjust
To add 199, add 200 and subtract 1. To multiply by 19, multiply by 20 and subtract one lot of the number.
2. Multiply by 5 by halving and tens
34 × 5 = (34 × 10) ÷ 2 = 340 ÷ 2 = 170. Quicker than long-multiplying.
3. Use complements for subtraction
1000 − 367: count up from 367 to 1000. 367 → 400 (33), 400 → 1000 (600). Answer: 633. Practice now on word problems to apply these.
4. Halve and double
To multiply 16 × 25, halve and double: 8 × 50 = 400.
5. Spot the easy fraction
75% = three quarters. 60% = three fifths. Recognising these saves working from scratch.