Mental maths tips

The fastest players are not doing harder maths. They split every problem into steps they already know by heart.

Addition

Work left to right. Add the tens first, then the ones: 47 + 38 is 70 + 15, which is 85. You read numbers left to right, so you can start before you have finished reading.

Round, then adjust. When one number sits next to a round number, use it: 67 + 29 is 67 + 30 − 1, which is 96.

Subtraction

Count up instead of down. For 143 − 58, go from 58 to 60 (2), then to 100 (40), then to 143 (43). Add the jumps: 85.

Remember what you are looking for. On the default settings, subtraction is always addition in reverse, so the answer is between 2 and 100.

Multiplication

Split the bigger number. 7 × 86 is 7 × 80 plus 7 × 6, so 560 + 42, which is 602.

• × 5: times 10, then halve. 5 × 64 is 640 ÷ 2, so 320.
• × 9: times 10, then take one lot away. 9 × 47 is 470 − 47, so 423.
• × 11: times 10, then add one lot. 11 × 58 is 580 + 58, so 638.
• × 12: times 10 plus times 2. 12 × 37 is 370 + 74, so 444.

Division

Turn it into a times table question. 602 ÷ 7 asks what times 7 makes 602. Find the tens digit first: 7 × 80 is 560, leaving 42, and 42 is 7 × 6. So the answer is 86.

On the default settings the number you divide by is always between 2 and 12, and the answer always comes out whole.

Habits that add points

• Never press Enter. A right answer is accepted the moment you type its last digit.
• Start typing early. Once you know the first digit, type it while you work out the rest.
• Keep your eyes on the problem, not your hands. On a laptop, rest your fingers on the number row.
• Play a little every day. Short daily rounds beat a long weekly session. The daily challenge and your streak keep count.
• Drill your slowest tables. Your stats page ranks your weakest spots and shows a heatmap of every times table.

For trading and quant applicants

Some trading firms use timed mental arithmetic tests early in their hiring process. The default settings here are the ones most applicants practise with, so your default score is the number people tend to compare.

Practise on the default settings so your scores stay comparable, and use custom ranges to target a weak area.