At first glance, Sandra’s age puzzle looks easy, but many people arrive at different answers because they misunderstand the order of operations. The challenge presents a simple expression: 80 − 40 ÷ 10 × 4. Some people get 16 by calculating everything from left to right, while others arrive at 79 by assuming multiplication must always come before division.

To find the correct answer, we must follow the standard mathematical rules known as PEMDAS or BODMAS. Parentheses and exponents come first, followed by multiplication and division, which have equal priority. Addition and subtraction also share the same priority. Whenever operations have equal priority, we calculate from left to right.

Starting with Sandra’s expression, we perform the division first: 40 ÷ 10 = 4. The expression now becomes 80 − 4 × 4. Next, we multiply 4 by 4 to get 16. Finally, we subtract: 80 − 16 = 64. Therefore, using the standard order of operations, the correct answer is 64.

Parentheses can change the result dramatically. For example, (80 − 40) ÷ 10 × 4 equals 16, while 80 − 40 ÷ (10 × 4) equals 79. However, the original expression contains no parentheses, so we must follow the usual rules without adding any. 🤔 Did you get 64 on your first attempt, or did this tricky puzzle catch you off guard?