Quick Sums

A minute on the clock and one sum at a time. Key in the answer and, if it is right, the next sum is already there. After every fifth correct answer the numbers step up.

How a run works

Pick a level: addition, subtraction, multiplication, division, the four mixed, or percentages. Answers are whole numbers, never negative, so the keypad has only digits on it.

Type the answer. If it is right, the next sum appears at once, with no button to press. OK sends a wrong answer, or skips a sum you would rather not do; either way it counts as wrong.

Five bands of numbers stand between the first sum and the last. Each fifth correct answer moves you up a band: addition opens with one-digit sums and ends with three-digit ones. The figure that counts is how many you got right in the minute; wrong answers, accuracy and the average seconds per answer sit next to it.

Speed tactics

• Add from the left: 47 + 38 is 70 + 15, so 85.
• Subtract by counting up: from 47 to 50 is 3, from 50 to 83 is 33, so 83 − 47 = 36.
• Divide by asking a times-table question: 72 ÷ 8 is 'what times 8 makes 72?'
• Percentages: 10 % is a tenth, 25 % a quarter, 15 % is 10 % plus half of that, 75 % is three quarters.
• Multiplying by 5 is half of multiplying by 10: 5 × 18 is 180 halved, so 90.
• Skipping is a tool. A sum that would take eight seconds costs you two easy ones; send it with OK and move on.
• Expect a slower answer right after 5, 10, 15 and 20 correct: that is where the numbers jump.

Questions