How to play Number Pyramid

Fill every brick so that each one equals the sum (or product) of the two bricks directly below it. Also known as Addition pyramid, Brick wall, Number wall.

▶ Play Number Pyramid ⊞ Open the solver

The rules

Bricks are stacked so each one rests on two bricks below.
In an addition pyramid, each brick equals the sum of the two below it.
In a multiplication pyramid, each brick equals their product.
Given bricks can’t be changed.

Playing Number Pyramid on Puzzle Solvers

Choose add or multiply, how many rows and a difficulty, then press New Puzzle.
Tap a brick and type its number on the pad (or keyboard). Tab or ↵ jumps to the next empty brick.
With checking on, a brick turns green when it matches the two below it, red when it doesn’t.
Hint shows the next brick to work out — and whether to add, subtract, multiply or divide.

Open the Number Pyramid game →

Using the Number Pyramid solver

Type the bricks you know (or press Sample).
Press Solve and step through each brick: adding up, taking away, and algebra when two bricks are missing side by side.

Open the solver →

A worked example

A brick shows 20 and the brick under its left side shows 12. The brick under its right side must be 20 − 12 = 8.

Now 8 and its right-hand neighbour 5 give the brick above them: 8 + 5 = 13.

Strategies

Work up. Two bricks side by side give the one above them: add them.
Work down. A brick and one of its supports give the other: subtract (or divide).
Look for triangles. Every brick and the two below make a little triangle — any two numbers in it give the third.
Algebra. If two neighbouring bottom bricks are missing, call one ‘a’ and write the others in terms of it; the top brick gives an equation.
Pascal’s pattern. The top of a 4-row pyramid is a + 3b + 3c + d from the bottom row — the numbers 1, 3, 3, 1.

Common mistakes

Adding when you should subtract (working down the pyramid).
Using the wrong pair of supporting bricks.
In multiplication pyramids, dividing in the wrong direction.

Where it comes from

Number pyramids (also called number walls) have been used in maths classrooms for decades to practise addition and subtraction and as a gentle first step into algebra.

Frequently asked questions

Which age is it for?

3-row addition pyramids suit ages 5–6; 5-row and multiplication pyramids suit 8–11; algebra pyramids suit 11+.

Can bricks be negative?

Not in generated puzzles; the solver accepts negative numbers.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

How do I check a pyramid from a worksheet?

Open the Number Pyramid Solver, type the bricks you know and press Solve.

Keep going

All guides: How to play every puzzle and game.