What's Your IQ

Mental Math

One minute, as many sums as you can. No pencil, no calculator, just you and the numbers. Arithmetic fluency is one of the most practice-sensitive skills there is: a few minutes a day makes a visible difference within a week.

Difficulty

+Add−Subtract×Multiply÷Divide

EXAMPLE ROUND · PLAY TO SEE YOURS

Where the seconds went

Most people are quick on addition and stall on one operation. Find yours, then drill it with the shortcuts below.

AVERAGE TIME PER ANSWER, BY OPERATION

+1.7 s100% right

−2.1 s80% right

×3.4 s80% right

÷3.3 s100% right

Multiply is your slowest at 3.4 s an answer. Times tables to 12 are worth memorising outright; the shortcuts below help beyond that.

YOUR PACE ACROSS THE MINUTE

first answerbar height = seconds takenlast

23correct

88%accuracy

−23%2nd half vs 1st

HOW FAST CALCULATORS THINK

Six shortcuts, step by step

Speed in mental arithmetic rarely comes from calculating faster. It comes from turning a hard sum into an easy one. Pick a trick, then press "new example" to see it work on fresh numbers.

THE PROBLEM17 × 11= 187Works for any two-digit number.

1Split the number into its digits.1 _ 7

2Add the two digits and put the sum in the middle.1 + 7 = 8

3Read the result.1 8 7 → 187

WHAT THIS GAME TRAINS

Number fluency under time pressure

Mental arithmetic mixes fact retrieval (knowing 7 × 8 instantly) with working memory (carrying digits while you calculate). Speed comes from moving more sums into the first category.

corestrongsomelight

coreArithmetic fluencyRecalling number facts and procedures automatically.

strongWorking memoryHolding partial results, like a carried 1, while you continue.

strongProcessing speedReading each problem and typing an answer fast.

someNumber senseEstimating whether an answer is roughly right.

OUTSIDE THE GAME

Where you'll notice it in everyday life

01Everyday sumsSplitting bills, checking change and comparing prices in your head.

02Splitting the billWorking out shares and tips at the table without a phone.

03Work confidenceQuick estimates in meetings, budgets and spreadsheets.

INSIDE YOUR BRAIN

The brain areas doing the work

Step through each area, or tap one below. The matching marker grows on the brain; dashed markers sit deep inside.

Side view of the brain with the four lobes shaded in different colours

Based on Gray's Anatomy, fig. 728 (public domain)

AREA 1 OF 4

1Parietal lobetop and back

Combines what you see, hear and touch into a map of where things are. It also handles numbers and directing your attention through space.

ITS JOB IN THIS GAMETracks where things are and how many there areThe intraparietal sulcus represents quantities and is active in almost every calculation.

DID YOU KNOWDamage on the right side can make people ignore everything on their left, a condition called hemispatial neglect.

ALL AREAS

WHERE TO GO FROM HERE