What is 9 – 3 ÷ 1/3 + 1 ?

This seemingly simple math problem went viral in Japan after a study found that only 60% of 20-somethings were able to calculate the correct answer, down from a rate of 90% in the 1980s.

Of course the key is order of operations.

Shopping Medicare in the digital age is as simple as you make it.

1. Parentheses
2. Exponents
3. Multiplication and Division (left to right)
4. Addition and Subtraction (left to right)

(As the famous mnemonic goes, Please Excuse My Dear Aunt Sally.)

What’s your final answer? Let’s let the good people at Mind Your Decisions walk us through it:

Ready to try another?

Considerable

Here’s another math problem along the same lines. Go check your answer here.

The bus problem

Which way is this school bus going? Children do better on this problem than adults. Here’s the answer.

Last one

If you’re still in a brain teaser mood but have had enough math and logic for one day, go try to spot the leopard (I promise it’s there).