Number Pyramid Puzzle Generator

Addition pyramids are a staple of primary maths because they practise addition and subtraction in the same puzzle: you work upwards by adding and downwards by subtracting, and a good puzzle makes you do both. The thing that separates a good one from a frustrating one is whether it can actually be finished by reasoning. This removes bricks only while the puzzle still solves by arithmetic alone, so no pupil ever needs to guess.

Rows

The bottom row's width. More rows means bigger numbers at the top.

Largest starting number

Keeps the top of the pyramid within reach.

Seed (optional)

Reproduces the same puzzle — useful for a class set.

Your number pyramid will appear here.

What this generator does

Guarantees solvability, which a hand-made pyramid does not. The missing-number puzzles on this site set an equation with a gap; this builds a whole structure where the gaps interact. Bricks are removed one at a time and each removal is only kept if the puzzle still resolves using the two obvious rules — a brick from the pair beneath it, and a missing brick beneath from its parent and its sibling. Anything requiring a guess is put back.

How to use this tool

Choose how many rows and the largest starting number.
Make a puzzle.
Work up by adding pairs and down by subtracting.
Use a seed to make the same puzzle for a whole class.

Understanding the controls

Rows: The width of the bottom row, three to seven. More rows means larger numbers at the top, because every level roughly doubles.
Largest starting number: Caps the values on the bottom row. Keep it small for younger pupils — a seven-row pyramid from numbers under 20 still reaches the hundreds at the apex.
Seed: Reproduces the same puzzle, so a whole class can work on one, or so an answer key stays valid.

Worked examples

Base row 1, 2, 3: Builds to 3, 5 and then 8 at the apex.
A five-row pyramid: Fifteen bricks, typically six or seven given.
Working downwards: A missing brick below is its parent minus its sibling — subtraction practice.
The same seed: The identical puzzle, every time.

Common use cases

Setting differentiated addition practice by changing the row count
A quick starter or plenary that needs no preparation
Practising subtraction as the inverse of addition rather than as a separate skill
Making a printable worksheet with a known answer
Homework where every child gets the same puzzle, or a different one

How this generator works

A random bottom row is generated and the pyramid is built upwards by addition. Bricks are then removed in a random order, and after each removal the tool tries to solve what is left using only the two rules a pupil would use. If the puzzle no longer resolves completely, the brick goes back. What you get is the most open puzzle that is still solvable by reasoning — and that solvability is re-checked before the puzzle is shown.

Randomness and fairness

Randomness picks the starting numbers and the order bricks are considered for removal. Solvability is not random — every candidate removal is tested, and one that would force a guess is undone. With a seed the whole puzzle is reproducible through a documented non-cryptographic generator: that path is for repeatability, not for anything that needs to be unguessable.

For how randomness is produced across the whole site, see how Generate Random works.

Assumptions this tool makes

Solvers use only the two standard rules: add upwards, and subtract to fill in below.

Limitations and good to know

Addition only. Pyramids using multiplication or subtraction between bricks are a different puzzle and are not produced.
The numbers can get large at seven rows; that is inherent to the doubling, not a setting.
It does not check that a puzzle has a *unique* solution, only that it can be completed by the standard rules — for this puzzle type those amount to the same thing in practice.
Nothing is saved between visits, so note the seed if you need the puzzle again.

Common mistakes

Only working upwards: Most puzzles need you to come back down as well, subtracting a known brick from the one above. That is the half that makes it worth setting.
Choosing seven rows for young pupils: The apex will be in the hundreds or thousands. Four or five rows with small starting numbers is usually the right level.

Practical tips

Use a seed and print two copies — one to work on, one as the answer key from the reveal button.
Give the same seed to the whole class so the discussion afterwards is about one puzzle.

Privacy and your data

Everything is computed in your browser from the settings you choose. There is nothing to upload, nothing is stored between visits, and no settings are written into the page address. Analytics records that the tool ran and how many rows the puzzle had.

Frequently asked questions

Can every puzzle be solved without guessing?: Yes. Each brick is only removed if the remaining puzzle still resolves using the two standard rules, and the whole puzzle is re-checked before it is shown.
Why do the numbers get so big?: Because each row is the sum of the one below, so values roughly double every level. Reduce the starting numbers or the row count to keep them manageable.
Can I get the same puzzle twice?: Enter a seed. The same seed and settings always produce the identical puzzle, which is what a class set needs.