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How to play
Goal
Fill every empty brick so that each brick equals the sum of the two bricks directly below it.
How it works
- Brown bricks are given. Tap an empty brick and type its number with the keypad (or your keyboard). ⌫ deletes a digit.
- Each brick rests on two bricks. Top = left + right below it.
- When every brick is filled, any brick that doesn't add up turns red.
- Every pyramid can be worked out step by step, without guessing.
- 3 rows use small numbers and are great for young players. 5 rows are a real workout.
Example
If the two bricks below are 3 and 5, the brick on top is 8. If a brick is 8 and one of the bricks below it is 3, the other must be 8 − 3 = 5.
Tips
- Look for any brick where two of the three numbers (the brick and its two supports) are known. The third is a quick sum or subtraction.
- Sometimes you need to work downwards with subtraction, not just upwards with addition.
The history of Number Pyramid
Number pyramids, called Zahlenmauern (“number walls”) in Germany, are a favourite in primary-school maths there and in many other countries. They practise adding and subtracting while quietly teaching algebra.