Novelist Celeste Ng has shared a head-scratching system of equations that her 9-year-old son apparently made up over dinner: At dinner, 9yo made up a math problem and made his father and me solve it.

A seemingly simple math problem has gone viral this week, leaving people totally stumped on social media. The equation in questions is: 15 - 15 × 4 ÷ 2 = ? At first glance, it looks like a basic grade ...