At one time or another, most adults have been roped into helping a grade-schooler with his or her homework. Usually, it’s a bit of an ego boost to have a pre-teen look at you like some sort of modern-day Euclid when you start dropping terms like “equilateral triangle.” But one particular math problem left six- and seven-year-old students in the UK stumped—and their parents scratching their heads.

The math problem, which you can see below, was originally posted to Twitter by Louise Bloxham, a mom in England who was shocked that the question was on her second-grader’s standard assessment test.

The post quickly went viral, with adults around the world weighing in on the unnecessary pressure that standardized testing puts on kids—and many admitting that they themselves couldn’t figure out the answer. (Which, if you haven’t figured it out, is 65.)