Man pranks girlfriend with maddeningly simple maths riddle – can you solve it?

By Saskia Hill
31 March 2016

We bet you've heard this one before - but it's much tougher than it seems!

A man left his girlfriend totally stumped with this seemingly simple riddle.

The hilarious exchange  between the couple, which was posted online by YouTuber xmintyx, sees them debating an age-old riddle in bed.

Read more: This sassy fourth grader schooled her teacher in girl code on ‘inappropriate’ maths question

The riddle in questions? An older brother is fours years old and his younger brother is half his age. How old would the younger brother be if the older one was 100 years old?

The woman in the video is convinced the answer is 50 because the younger brother is half his older brother’s age.

“How is it not 50?” she asks her boyfriend. He repeatedly assures her the answer isn’t 50 and asks her to try again. After many attempts she gives up and her boyfriend explains the riddle to her.

Like all riddles the trick is in the wording of the question. The secret is not to focus on the younger brother who’s half his older brother’s age.

The answer: the younger brother is only two years younger than his older brother, which was half his brother’s age when the brother was four.

Read more: Can you solve it? This school maths question has left the world stumped

The woman’s boyfriend eventually manages to make it clear to her that the younger brother would be 98 if his older brother was 100.

“I think you’ve got this wrong,” she says before she suddenly gets the riddle and bursts out laughing.

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