Four Operations Pyramids: Add, take away, times and divide, all in one pyramid. This is one of the many kinds of math pyramid we make, and here is how it works, with a video, a worked sample and a pyramid you can try right on this page.
The rule
Each brick is made from the two bricks under it with the operation shown on it. Division always comes out exact.
A worked sample
Undo the times
The top is left × 12 = 36. To undo a times, divide: 36 ÷ 12 = 3.
Undo the divide
The left brick of row 2 is 12 ÷ ? = 3. To find the number you divided by, divide again: 12 ÷ 3 = 4.
Undo the other times
The right brick of row 2 is 4 × ? = 12, so ? = 12 ÷ 4 = 3. All four operations were used, and every check works.
Your turn
Try it: all four operations
Each brick shows its operation. Work backwards from the numbers you can see, then press Check.
Why it is worth doing
Division is the new twist: dividing undoes times, and dividing again undoes a divide. Spotting which inverse to use is the skill.
Books mentioned
Four Operations Math Pyramids
124 pyramids that add, subtract, multiply and divide, for teens and adults. Full solutions are in the back.
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