Brick pyramids where each brick is the two below added together. Five levels from 3 rows to a four-floor detective puzzle, with a printable worksheet.
A number pyramid is a stack of bricks. Each brick holds the sum of the two bricks directly under it, so a bottom row of 2, 3 and 4 gives a middle row of 5 and 7 and a top brick of 12. Your child fills the empty bricks. The skill is the heart of early algebra: using addition forwards and backwards. Finding the top brick is addition. Finding a hidden brick in the middle or at the bottom is subtraction in disguise, because 12 minus 5 tells you the other part of 5 plus 7. Children practise fact families without a drill, and every brick gives immediate proof, because a wrong number breaks a sum somewhere else in the pyramid. It builds the habit of checking an answer against a second clue, which is the habit that school and contest problems reward.
Level 1, Build up, shows the whole bottom row of a 3-row pyramid with numbers from 1 to 5. The child adds upwards to fill the two middle bricks and the top. Level 2, Missing brick, hides one or two bricks anywhere, with bottom numbers up to 9, so at least one brick has to be found by taking away. Level 3, Work it out, shows only three of the six bricks. The child must decide which brick to find first. Level 4, Four floors, is a 4-row pyramid with ten bricks, four shown and six hidden. Level 5, Detective, shows only three or four bricks of a four-floor pyramid. When three bricks are shown, the puzzle can only be solved by also using the rule printed in the question, that every bottom brick is a number from 1 to 9. This is the kind of reasoning used in children's maths contests, and it is hard for age 6 and 7. Start at level 1 and let the game adapt: three wins in a row go up a level, two misses in a row go down one.
Nothing is stored in advance. For each puzzle the game picks a random bottom row, builds the full pyramid by adding upwards, and then hides bricks. On levels 1 to 4 a hidden pattern is kept only if the whole pyramid can be rebuilt by a simple rule: whenever a brick and its two supports have exactly one unknown, that unknown is forced. Each step is either an addition or a subtraction, so there is exactly one answer and a child can always find a next move. On level 5 with three shown bricks, the game counts every possible bottom row from 1 to 9 and keeps the puzzle only when exactly one pyramid fits. The tests repeat that count with a separate program for 500 puzzles on every level. The number tiles are the numbers that belong in the hidden bricks plus a few near misses, never more than nine tiles in all.
The print option makes a worksheet of 4, 6 or 8 new pyramids at the level you choose, on Letter or A4 paper, with an answer key on the last page. Each print is freshly generated, so a second worksheet is different from the first. The PDF is built in your browser and nothing is uploaded. The game does not use a timer, does not take points away, and shows no ads inside the play area. It does not teach place value or carrying, because the numbers stay small, and it does not replace a teacher. A 6-year-old should be able to finish level 1 alone on the first day. Levels 4 and 5 are meant to be solved together, with a pencil, and talked through.
Ages 6 to 8. Level 1 only needs adding two numbers up to 5 and works for a first-grader. Levels 4 and 5 use 4-row pyramids with bricks up to about 70 and suit a strong 7 or 8 year old.
No. Every puzzle is checked before you see it. On levels 1 to 4 each hidden brick is forced by a sum with one unknown. On level 5 the game counts all bottom rows from 1 to 9 and keeps the puzzle only when exactly one fits.
With only three bricks shown, a four-floor pyramid can have several answers if any whole number is allowed. The 1 to 9 limit is part of the puzzle, and it is what makes the answer unique.
Yes. Pick a level, choose 4, 6 or 8 pyramids and Letter or A4 paper. Each worksheet is new, and the answer key is on the last page.
When a brick on a lower floor is hidden, the child works out which number added to its neighbour gives the brick above. For example 12 on top of 5 and an empty brick means 12 minus 5 is 7. The pyramid checks the answer itself.
No. Puzzles are made in your browser and progress such as stars and level stays on this device. The page counts visits with Google Analytics, never answers.