Can you find the number?

Puzzles are not just a fun way to pass the time.  They can also give your brain a useful workout.

Solving puzzles may help improve logical and analytical thinking. They can also support problem solving skills and memory by making the brain look for patterns and connections.

The puzzle shown above is a simple-looking challenge that can leave many people confused.

The image shows three boxes filled with crossing lines. A number is written next to the first two boxes while the third box has a question mark. Your task is to figure out which number should replace the question mark.

The first box has the number 9, while the second box has the number 1. So how was each number calculated?

The answer becomes clear when you look closely at the lines inside each box. In the first box the lines cross each other at 9 points.

In the second box, they cross at only 1 point. Now look at the third box. Its lines cross each other at 4 points.

So, the correct answer is 4.

Did you spot the pattern?