Math 123

About Math 123

Math 123 is a mental-arithmetic game built on just three numbers. Every question is a short sum of ones, twos and threes, added or taken away, and every answer is 1, 2 or 3. That sounds easy, and for the first few questions it is. Then the sums get longer and the clock gets shorter.

A round starts with two-number sums and ten seconds a question, then moves to three, four and five numbers while the time drops to nine, seven and five seconds. From question 51 you have four seconds each. One wrong answer, or running out of time, ends the round. Your record is how many questions you answered correctly, and the leaderboard is monthly: it resets on the 1st of every month at 00:00 UTC.

How to play

1. Press Start. A sum appears with three buttons: 1, 2 and 3.
2. Work out the sum and tap the answer — or press 1, 2 or 3 on your keyboard — before the time bar runs out.
3. A right answer brings the next question at once. The sums grow from two numbers to five as the round goes on.
4. Stuck on one? Press Skip. You have one skip per round, or four if you watch a short video before you start.
5. A wrong answer or a timeout ends the round. Once per round you can watch a short video to carry on with the next question.
6. You can start three rounds an hour, and one more each hour after a short video.

Tips

• Cancel pairs before adding: in 2 + 1 − 2 + 3 − 3, the 2 and −2 cancel, and so do the 3 and −3, leaving 1.
• Count in steps rather than holding the whole sum: start from the first number and move up or down.
• A leading minus only means you start below zero: −1 + 2 is two steps up from −1.
• Keep your skip for the five-number sums, where the time is shortest.
• The answer is always 1, 2 or 3. If your total comes out as 0 or 4, you have slipped somewhere — look again.

Questions players ask