plus sign contains:

• 1 vertical line
• 1 horizontal line

They cross exactly once:

1 × 1 = 1

Now the pattern becomes much easier to see.

What About the Missing Number?

The final figure contains 2 vertical lines and 2 horizontal lines.

Following exactly the same rule:

2 × 2 = 4

So the missing number is:

4

Why Is This Puzzle So Easy to Get Wrong?

The shapes encourage you to count boxes, corners, or enclosed spaces. Your brain naturally tries to recognize the overall shape instead of examining how the individual lines interact.

That’s the trick.

The puzzle isn’t really testing complicated mathematics. It’s testing whether you can look past the obvious interpretation and identify the underlying rule.

Final Answer: 4

Did you spot the intersections, or did you start counting the squares first?