Mental Math Game for Adults: 12 Problems Against the Clock

A mental math game for grown-ups

Most mental math games online are built for kids: times tables, cartoon rewards, levels named after grades. This one is the Math game from Memo, made for adults who want a fast, honest workout: twelve problems, a clock, and nothing else. It is the same idea as the calculation drills in Nintendo’s Brain Age — simple arithmetic, done as fast as you can. (More on where that idea came from below.)

How a round works

1. 4 warm-ups: single-digit addition, subtraction and small multiplication.
2. 5 two-digit problems that make you carry or borrow (47 + 38, 72 − 45) or multiply up to about 14 × 6.
3. 3 harder ones: three-number chains like 38 + 27 − 19, or 16 × 5.

Type your answer on the keypad or keyboard. It checks itself as soon as you have typed enough digits, so there is no “enter” key to slow you down. A wrong answer flashes red and you go again. Your score is the total time, so a mistake costs you seconds, not the round.

Tricks that make you faster

Add from the left

School teaches you to add right to left with carrying. In your head, left to right is faster: 47 + 38 → 40 + 30 = 70, 7 + 8 = 15, total 85. You say the big part of the answer first and adjust.

Round and compensate

Numbers ending in 7, 8 or 9 are easier to round: 47 + 38 = 47 + 40 − 2 = 85. The same works for subtraction: 72 − 45 = 72 − 50 + 5 = 27.

Split multiplication

Break the bigger number into tens and ones: 14 × 6 = 10 × 6 + 4 × 6 = 60 + 24 = 84. For 16 × 5, halve and double: 8 × 10 = 80.

Chains: pair what cancels

In 38 + 27 − 19, notice that 27 − 19 = 8, then 38 + 8 = 46. You are allowed to reorder addition and subtraction, so look for the pair that is easiest first.

Read the whole problem first

Half a second spent spotting the trick saves two seconds of brute force. Speed comes from choosing the method, not from typing faster.

Where mental math games come from

People have done sums in their heads for as long as they have traded, but the best-known training method is the abacus. Counting boards were used in ancient Rome and Babylon, and the Japanese soroban is still taught today. Its most skilled users stop needing the frame: they picture the beads and move them in their heads, a technique called mental abacus. Experiments with children in India suggest that practiced users hold the imagined abacus in visual memory, column by column, and that talking during a calculation barely slows them down.

The modern brain-game version starts in Japan with neuroscientist Ryuta Kawashima of Tohoku University. Brain-imaging research had linked reading aloud and simple arithmetic to activity in the prefrontal cortex on both sides of the brain, and Kawashima wrote drill books for adults built on those two activities. His calculation and reading-aloud drills came out from Kumon in November 2003 and became very popular. On December 2, 2004, the day the Nintendo DS launched in Japan, Nintendo president Satoru Iwata visited him with prototype software. As the two recall in an Iwata Asks interview, Brain Age followed in May 2005, and its sales in Europe eventually overtook those in Japan.

Kawashima’s team also tried the drills in a small 2005 clinical study with 32 older adults with Alzheimer-type dementia. That was a supervised six-month program for one specific group, and it says nothing about what a game like this one does for healthy adults.

Why practice mental math as an adult?

• It is useful. Tips, discounts, splitting a bill, checking a quote — daily life is full of quick arithmetic.
• It is measurable. Time per problem is a clean number, so you can actually see progress.
• It is a good focus exercise. You cannot do it while thinking about something else.

Does it improve your brain? What the research says

Practice reliably makes you faster at arithmetic itself. Claims that it sharpens your mind in general are a different matter.

• Arithmetic practice improves arithmetic. In a randomized trial at a school in India, 204 children aged 5 to 7 spent three years getting either three hours a week of mental abacus or three hours of extra regular math. The abacus group did better on arithmetic, but the training did not change basic abilities like working memory; children who started with stronger spatial memory simply learned the technique better.
• A small Brain Age trial was encouraging. Kawashima’s group randomly assigned 32 older adults who rarely played video games to Brain Age or Tetris, about 15 minutes a day, at least five days a week, for four weeks; 28 finished. The Brain Age group gained more on tests of executive function and processing speed, but not on overall cognition or attention. The authors call for larger replications, and note that Kawashima created Brain Age and his university receives royalties from it.
• Large studies find little transfer. In a BBC-run study, 11,430 adults trained at least 10 minutes a day, three times a week, for six weeks. They improved on every trained task, but did no better on untrained tests than a group that answered trivia questions online.
• Nerves eat into working memory. In experiments by Ashcraft and Kirk, people with high math anxiety had smaller working-memory spans, and they slowed down and made more errors on mental addition while holding something else in mind. The authors describe this as a temporary disruption of working memory, not a fixed limit.

Put together: expect to get faster and more confident at the arithmetic you practice, which is useful on its own. A 2016 review of brain-training studies found little support for bigger promises, so keep expectations to what you train. If you like the time pressure, try the Stroop test; if you prefer puzzles, the missing-angle puzzles are a slower kind of math.