Find the missing number If you... - Brain teasers and puzzles ... - Free Printable

Let's solve this step-by-step.

We are given four triangles, each divided into four smaller sections:

- Top triangle: numbers 2 (top), 1 (bottom-left), 3 (bottom-right), and 5 (center)
- Second triangle: 2 (top), 2 (bottom-left), 11 (bottom-right), and 26 (center)
- Third triangle: 4 (top), 3 (bottom-left), 2 (bottom-right), and 18 (center)
- Fourth triangle: 2 (top), 3 (bottom-left), 6 (bottom-right), and ? (center)

Our goal is to find the missing number in the fourth triangle.

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Step 1: Look for a pattern

Let’s examine the first three triangles and see if we can find a relationship between the numbers.

Each triangle has:
- A top number (T)
- A bottom-left number (L)
- A bottom-right number (R)
- A center number (C)

We want to find a formula such that:
C = f(T, L, R)

Let’s test the first triangle:

#### Triangle 1:
- T = 2
- L = 1
- R = 3
- C = 5

Try:
Is 5 = 2 + 1 + 3? → 6 → No
Is 5 = 2 × 1 + 3? → 2 + 3 = 5 → Yes!
But let’s check others.

Wait — maybe try multiplication or other combinations.

Try:
T × L + R = 2×1 + 3 = 5 → matches
Check second triangle:

#### Triangle 2:
- T = 2
- L = 2
- R = 11
- C = 26

Try: 2×2 + 11 = 4 + 11 = 15 ≠ 26 → no

Try: T × R + L = 2×11 + 2 = 22 + 2 = 24 ≠ 26

Try: L × R + T = 2×11 + 2 = 22 + 2 = 24 → still not 26

Try: T × (L + R) = 2×(2+11)=2×13=26 → YES!

So: T × (L + R) = 26

Check triangle 1: T × (L + R) = 2 × (1 + 3) = 2 × 4 = 8 ≠ 5 → No

Not consistent.

Wait — try another idea.

Try: L × R + T = ?

Triangle 1: 1×3 + 2 = 3 + 2 = 5 → YES!

Triangle 2: 2×11 + 2 = 22 + 2 = 24 ≠ 26 → No

Nope.

Try: T × L × R?

Triangle 1: 2×1×3 = 6 ≠ 5

No.

Try: (T + L) × R?

Triangle 1: (2+1)×3 = 3×3 = 9 ≠ 5

No.

Try: (T + R) × L?

(2+3)×1 = 5×1 = 5 → YES

Triangle 2: (2 + 11) × 2 = 13×2 = 26 → YES!

Triangle 3: (4 + 2) × 3 = 6×3 = 18 → YES!

Perfect!

So the pattern is:

> Center number = (Top + Bottom-right) × Bottom-left

Or written as:
C = (T + R) × L

Let’s verify all:

Triangle 1:

- T = 2, R = 3, L = 1
- (2 + 3) × 1 = 5 × 1 = 5 → Correct

Triangle 2:

- T = 2, R = 11, L = 2
- (2 + 11) × 2 = 13 × 2 = 26 → Correct

Triangle 3:

- T = 4, R = 2, L = 3
- (4 + 2) × 3 = 6 × 3 = 18 → Correct

Now apply to Triangle 4:

- T = 2
- R = 6
- L = 3
- C = (2 + 6) × 3 = 8 × 3 = 24

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✔ Final Answer: 24

The missing number is 24.