A small pyramid made of number bricks is puzzling thousands of people online. One brick is missing, and every other number is a clue. Can you find it?
Some puzzles do not need a long question. A few boxes and a few numbers are enough to keep your brain busy for several minutes. The number pyramid puzzle is one of those classic challenges. It looks like a simple stack of bricks, but it quietly tests your addition, your logic, and your patience at the same time.
In today’s puzzle, you will see a four-level pyramid. The top brick shows 43. The second level shows 21 and 22. The bottom level has four bricks: 4, ?, 3, 9. Your task is to find the number hiding under the question mark.
(Also read: Number Series Puzzle: Can You Find the Missing Number in 2, 6, 12, 20, 30?)
Number Pyramid Puzzle: Can You Find the Missing Brick?
At first glance, you might think you only need to add the numbers at the bottom. But the missing brick is on the bottom row itself, so you cannot start from there. Instead, you have to read the pyramid in a different direction. That small change in thinking is what makes this puzzle interesting. If you enjoy missing-number challenges, you may also like our number series puzzle.
Here is the rule of the pyramid: every brick is the sum of the two bricks directly below it. That means the top brick 43 comes from adding 21 and 22. The same idea works for every other brick. Once you understand this one rule, the pyramid starts to talk to you.
Here is a hint before you check the answer. Look at the third level, which has three hidden bricks. Only one of them can be worked out from the numbers you already know on the bottom row. Start with that brick, and the rest will fall into place like dominoes.
Write the pyramid on paper and fill in each brick as you find it. This is much easier than trying to do it all in your head.
Show Answer
Number Pyramid Puzzle: Can You Find the Missing Brick?
Correct Answer: 7
Explanation:
Call the three bricks on the third level A, B and C, from left to right. The bottom row is 4, ?, 3, 9. Because each brick is the sum of the two bricks below it:
- C = 3 + 9 = 12. This is the only brick on the third level that we can find directly.
- The second level tells us B + C = 22. Since C = 12, B = 22 − 12 = 10.
- The second level also tells us A + B = 21. Since B = 10, A = 21 − 10 = 11.
- Now look at B again. B = ? + 3 and B = 10, so the missing number is 10 − 3 = 7.
Check: A = 4 + 7 = 11, B = 7 + 3 = 10, C = 3 + 9 = 12. Then 11 + 10 = 21, 10 + 12 = 22, and 21 + 22 = 43. Everything matches, so the missing brick is 7.
Why Number Pyramids Are Great for the Brain
This puzzle looks like a kids’ game, but it trains something very useful: working backwards. In many everyday problems, we know the final result and need to find a missing step. Budgeting, planning a trip, or even fixing a mistake in a bill all use the same kind of thinking.
A few simple tips for solving any number pyramid:
- Always start with the brick that has two known numbers right below it.
- Use subtraction when you know the top and one of the bottom bricks.
- Write every new number on the pyramid immediately, so you do not forget it.
- Check your final answer by adding upwards from the bottom row.
Try This Bonus Puzzle
Here is a smaller pyramid for you. The bottom row is 2, 5, 4. Each brick above is the sum of the two bricks below it. What number is written on the top brick?
Show Answer
Correct Answer: 16
The second level is 2 + 5 = 7 and 5 + 4 = 9. The top brick is 7 + 9 = 16.
If you solved both puzzles, share this post with a friend and see how fast they can find the missing brick. If you got stuck, do not worry. Try the steps again slowly, and the pattern will become clear.
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