Mental Math Test

Each sum has its own short time limit, shown as a bar. No calculator, no paper, no sign-up. You get your score, your average speed and a full review at the end.

Mental arithmetic uses three things at once: number facts you have memorised (7 × 8 is 56), working memory to hold partial results while you carry or borrow, and processing speed to do it before the clock runs out.

The five levels shift the load between them. Level 1 is almost pure recall. Level 2 adds carrying and borrowing with two-digit numbers. Level 3 is times tables and division. Level 4 mixes bigger products with percentages. Level 5 asks for two steps, or a shortcut such as multiplying by 11.

Every run uses freshly generated sums, so you can take it again without memorising answers. The levels and time limits stay the same, which makes your scores comparable from one attempt to the next.

Arithmetic is a subtest on the Wechsler adult intelligence scale, where it counts towards working memory. People who are quick at mental sums tend to score somewhat higher on IQ tests. The link is real but modest, because arithmetic speed depends a lot on practice and schooling.

That is the main difference from an IQ test. You can get much faster at mental maths in a few weeks of drills. Fluid reasoning, the ability to solve problems you have never seen before, changes far less with practice.

Our full IQ test has no arithmetic in it at all. It measures 5 visual reasoning skills instead. This test has not been normed, so your score shows how you did on these sums, not where you rank.

Multiplying a two-digit number by 11: add its digits and put the total in the middle. 23 × 11: 2 + 3 = 5, so 253. If the digits add to 10 or more, carry the 1: 48 × 11 = 4(12)8 = 528.

Squaring a number that ends in 5: multiply the first digit by the next number up, then write 25 after it. 35 × 35: 3 × 4 = 12, so 1225. 65 × 65: 6 × 7 = 42, so 4225.

Percentages: 10% is one tenth, so move the decimal point once. 25% is a quarter, so halve and halve again. 20% is 10% doubled. 25% of 84: half is 42, half again is 21.

Single-digit sums get 10 seconds because most adults answer them from memory in two or three. Level 5 sums get 25 seconds because they need two steps. The limits are generous on purpose: the aim is to find where accuracy starts to slip, not to rush you into typing errors.