What’s in the parentheses
Then multiplication and division, from left to right
Finally addition and subtraction
Let’s apply this rule to our familiar expression:
6 ÷ 2(1 + 2)
= 6 ÷ 2 × 3 (since 1 + 2 = 3)
And here we read from left to right:
6 ÷ 2 = 3, so
3 × 3 = 9
So the correct answer is 9, not 1!
Why do we miss this subtlety?
The answer is simple: our brains tend to group things that they perceive as related. The notation 2(1 + 2) looks like a priority multiplication, almost like a mathematical function. However, mathematics leaves no room for interpretation: the order in which operations are performed is decisive.
The Perfect Trap for Tired Brains
This little test is more than just an exercise: it’s a great way to stimulate our logic, test our discipline… and give us a little mental gymnastics.
No need for Sudoku or complicated escape room games: just a simple equation to get our brains working.
And between you and me, it’s also a nice reminder: our multitasking female brain, which can manage kids, work, meetings, and social life, can also use a few math rules!
The Magic of Math, Adult Version
Ultimately, this kind of little challenge shows how malleable our brains are… and sometimes a little rusty. But don’t panic: it’s never too late to revisit school memories, solve math puzzles over coffee, or challenge your friends with this school-worthy brainteaser.
So do you feel like offering someone else something else tonight?