- Puzzles9 shared a brain teaser with three pentagons, each with a set of five numbers.
- The middle pentagon is missing a number.
- To fill in the missing number, you must figure out the relationship between the numbers in the pentagons and continue the sequence.
- Can you solve it? Scroll down for the answer.

This brain-teasing maths problem created by Puzzles9 presents three pentagons, each with a set of five numbers. But here’s the catch – the middle pentagon is missing a number in the bottom right corner.

Can you figure out how all of the numbers are related and fill in the missing one?

Here’s the puzzle:

If you’re stumped, don’t worry. Here’s how to fill in that last number.

From left to right, let’s label the pentagons A, B, and C. The difference between the numbers in pentagons A and B can be found in Pentagon C in the same location across the board. In other words, Pentagon B – Pentagon A = Pentagon C.

For example, take the top row of numbers. A = 2, B = 5, and C = 3. Plugging in those numbers to our formula (B – A = C), we get 5 – 2 = 3, which is correct.

Now let’s use it to solve for the missing number in pentagon B, the bottom right.

B – A = C

B – 1 = 9

B = 10

The answer is 10.

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