ISSUE 001 · OCTOBER 15, 2026
Make the numbers work for you
Adding a number just below a round number? Round it up, then give back the difference.
Try 48 + 37. Think 50 + 37 = 87. You added two extra, so subtract two: 85.
This is called compensation. It is a useful option, not a rule you need to use for every problem. Try it with 59 + 26: 60 + 26 − 1 = 85.
Put your mental math to work →
New issues are planned weekly. This example is separate from the daily challenge, so it won’t spoil your game.