Mental arithmetic underpins every 11+ Maths paper, regardless of format. Children who calculate quickly and accurately have more time for harder questions.
What this question type tests
Mental arithmetic includes the four operations on whole numbers and fractions, percentages of common amounts (10%, 25%, 50%), and time/money calculations.
How it appears in real papers
11+ papers do not allow calculators. Children who hesitate on basic arithmetic burn time that should be spent on the higher-mark word problems. Recognising the question type within five seconds is the marker of a confident candidate; recognising it after thirty seconds of re-reading typically means a lost mark on a tight paper.
The technique to learn
The technique: drill specific patterns that appear repeatedly. 10% of any number, doubling and halving, multiplication by 11 (the cross-add trick), and quick fraction-to-decimal conversion all appear constantly.
Use a timer. The benchmark is 10 simple arithmetic questions in 60 seconds with full accuracy by the end of Year 5. Apps like Hit the Button make this fun.
Worked example
Worked example: 35% of 80. Method: 10% is 8; 30% is 24; 5% is 4; 35% is 28. Practise breaking percentages into 10%-and-5% chunks rather than calculating from scratch.
Common errors
Common error: skipping mental drill in favour of more "interesting" topic work. Mental arithmetic feels boring but yields disproportionate returns — every saved second on basic calculation is a second available for harder questions.
Practice approach
A 5-minute mental arithmetic drill at the start of every practice session, four times a week, transforms paper performance over a term. Embedding the technique requires repeated exposure across different surface presentations — a child who has only seen one phrasing will be thrown by the next.