A simple operation with identical numbers, and yet almost no one gets it right the first time. This little arithmetic challenge, which is circulating widely these days, hides a formidable trap. Rest assured, it’s not a question of intelligence—it’s a long-forgotten rule that’s resurfacing. We’ll explain everything calmly.
Why does our brain fall for it every time?
Imagine the following operation: 11 – 11 × 11 + 11. Instinctively, our brain takes the shortest path: it reads the calculation from left to right, exactly as we would read a text message or a shopping list. The direct consequence: we start by subtracting 11 – 11, we get 0, then we multiply by 11… and the result is completely wrong.
That’s precisely where the trick lies. This natural reading reflex makes us miss a rule that was taught well before high school. The problem? In our daily lives, we never really have the chance to remember it!
The fundamental rule that everyone has forgotten
It all comes down to the order of operations. In France, this rule is introduced in the early years of middle school: multiplication and division are always done before addition and subtraction—unless parentheses indicate otherwise, of course.
Here’s the order to follow so you never make a mistake again:
