Here’s a short math challenge that can cause surprising disagreements: 180 − 40 × 0 + 5 = ? Before grabbing a calculator, remember one basic rule of arithmetic.
What’s the correct answer?
The answer is 185.
Step-by-step explanation
According to the order of operations, multiplication comes before subtraction and addition. That means you first calculate 40 × 0 = 0.
Replace that product in the original problem and you get 180 − 0 + 5. Now calculate from left to right: 180 − 0 = 180, and 180 + 5 = 185.
Why is this question tricky?
Many people instinctively subtract 40 from 180 first because it appears first when reading from left to right. Others think the zero wipes out the entire expression. Neither is correct: multiplying 40 by zero makes only that product zero.
The same rule applies to similar quick mental-math challenges. Multiply first, then add or subtract. Did you arrive at 185 on your first attempt?
