Overview
- The viral expression 100 – 50 ÷ 5 × 2, which circulated widely Tuesday, equals 80 when you do division then multiplication left to right before subtracting.
- Reporters say the most frequent error is doing the initial subtraction first (100 − 50), which ignores the rule that multiplication and division take priority and are processed left to right.
- A second widely shared puzzle, (25 × 3 − 5) ÷ (4 + 3), was solved by outlets step by step to show the correct result of 10 after resolving parentheses and then division.
- Coverage from TN.com.ar, LA NACION and Diario Uno used these examples to teach PEMDAS/BODMAS and cited research from Princeton and Columbia’s Yaakov Stern linking regular mental calculation to cognitive benefits.
- Outlets framed the items as short social‑media brain teasers that test attention to detail, offer quick practice in basic rules, and serve as low‑cost exercises readers can use to stimulate thinking.