Classic brain training methods are perhaps puzzles like crosswords or sudoku, but in recent times I have become more and more attracted to the type of challenge you’ll see below.

These types of puzzles have been flooding the web lately, probably because they are really fun!

These are old classic mathematical problems. When you were in middle or high school.

These tests are more fun when you find yourself trying to remember the math you learned as a child.

**Can you figure out the correct solution?**

Here is the challenge, in the picture below.

At the top of the picture we see the task and then four possible answers.

Which solution do you think is the correct one?

How did you come up with it?

Take your time and think about it so you can find the correct solution.

Done? Below you can check if you picked the right number!

A

B

C

D

E

**The correct answer**

The correct answer is B: 12.

Why is 12 the correct answer?

Well, if you remember from your school days, according to the order of operations, you do multiplication before addition and subtraction, so you start by solving 3 x 3, which results in 9.

Then we are left with a simpler math problem: 3 + 9 – 3 + 3

**The answer is therefore 12.**

**Did you pick the correct number? Congratulations!**