The math problem, which was shared by Mumsnet user PeerieBreeks, seems simple enough. But then thousands of people argued over the right answer, and many were genuinely stumped. Here is the riddle:

A man buys a horse for $60. He sells the horse for $70. He then buys the horse back for $80. And he sells the horse again for $90. In the end, how much money did the man make or lose? Or did he break even?

Answers in the forum ranged from the man making $10, $20 and $30, while others argued he broke even. So what’s the answer?

A completely different riddle, so you don’t accidentally see the answer to the horse one

Answer to the filler riddle: a doughnut.


Back to the horse riddle

What seems to be confusing people is the fact that the man sells the horse for $70 and then buys it back for $80, making it appear like he spent 10 more dollars. But the correct way to solve the problem is to break it down and think of the two transactions as separate: -60 + 70 = 10 and -80 + 90 = 10. This means the man makes $10 with each sale, bringing the total to $20.

How did you do?


Would you like another?

If you raced through that one with ease, try another internet riddle that left people scratching their heads. (Answer here.)


And another?

Here’s a fourth grade math problem that also led to considerable debate. (Here’s the answer.)