Try Solving This Tricky Sibling Math Puzzle–How Many Children Are There in the Family?

June 6, 2020 Updated: June 6, 2020

“Thinking outside the box” means pushing the limits of your thinking. Riddles such as this one are a time-honored tradition for teaching you this important skill.

While storytelling and mythology are ways of transmitting life lessons to future generations, riddles spur you to think for yourself—a necessary ability in all cultures around the world. Riddles have, for a very long time, been a tool for developing this skill. This riddle is related to family relationships.

Family relationships can get complicated sometimes. Some families are large, and remembering names can get tricky. At family reunions, you may meet distant relations so obscure you may never unravel how you’re related—that Bob is, in fact, your mother’s brother’s wife’s second cousin!

Here, we have a tricky family puzzle involving siblings. See if you can solve it:

As you can see, this riddle involves some math as well, adding another level of complexity. Though it might seem simple at first, remember: riddles are not always as simple as they seem. Spend a moment to ponder what the answer is, and when you think you have it, or if you’re completely confounded by it, scroll down to see the solution.

The answer: There are 9 children in the family.

If you got this answer correct, congratulations! You successfully saw through the trickery. Yet, if you didn’t get the right answer, you may be scratching your head and wondering how it could be so. See the explanation below to find out:

Some people might have mistaken the riddle as being strictly a math problem without considering the family relationships and their implications. For example, there are eight brothers, each of whom has one sister, and some might have taken that to mean that there must, therefore, be eight sisters. Then, adding brothers and sisters together, there would be 16 children in the family.

Here’s where the problem lies: they are all in the same family. Therefore, each brother has one sister, yet that sister counts as the same sister for each brother regardless of how many brothers there are! Had there been eight sisters, then each brother would have eight sisters instead of one. It’s all about the relationship rather than simply the math!

If you enjoyed this tricky riddle, please share it with a friend or a co-worker to get their innovative juices flowing!