Only the Smartest People Can Figure Out This Tricky Logic Puzzle Without Looking at the Answer

July 14, 2020 Updated: July 14, 2020

Are you a puzzle pro? Test your mental prowess with this fun logic-based riddle and see if you can work it out without peeking at the solution!

Two Brothers, One Conundrum:

When a boy turned 4 years old, his younger brother was half his age. Try to figure out the age of the first boy’s younger brother as the first boy turns 18. The rest is up to you!

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Take a moment to yourself, grab a pen and paper if needed, or enlist the help of a friend or family member if you work better as a team. The answer, when you’re done puzzling, is posted at the bottom of the page. Good luck!

Epoch Times Photo
(Illustration – Morrowind/Shutterstock)


The Solution:

If the boy is 18, his younger brother is 16 years old! Did you get it right?


When the first boy was 4 years old, his younger brother was half his age—half of 4 is 2.

4 ÷ 2 = 2

So, from this we learn that the difference between the ages of the older boy and the younger brother is 2 years.

4  – 2 = 2

When the older brother turns 18, all we must do to find the younger brother’s age is subtract 2 years.

18 – 2 = 16

And, voila! We learn that when the older brother turns 18, the younger brother is 16 years old.

The Math:

For those who wish to flex their mathematical muscles and turn this puzzle into an equation, here’s how.

Let the boy’s age be x and the younger brother’s age be y

When x = 4, y = 4 ÷ 2
y = 2

Thus, the difference between the boy’s age and his younger brother’s age can be written as x – y = 4 – 2 = 2 years

So, when the boy turns 18, his brother’s age can be written as the following:

y = x – 2
y = 18 – 2
y = 16

Did you solve the riddle without peeking? If yes, give yourself a pat on the back for your patience, perseverance, and willpower!

Be sure to share this fun riddle with your loved ones and find out how many pro puzzlers you have in your midst.

Why Puzzle?

Quite frankly, it’s good for the brain. Dr. Susanne Jäggi at the University of Michigan has shared research with Men’s Health that claims 25 minutes of puzzling per day could raise the IQ by as much as four points.

2011 neuropsychological study of 488 senior living residents in Bronx County, New York, also spoke in favor of puzzles. “Cognitively stimulating leisure activities” such as visual, number-based, or crossword puzzles could delay the onset of memory decline in seniors, said the study’s authors.

The efficacy of puzzles lies in their demand upon the brain to compare new information with information already stored in the memory bank.

The psychologists Robert Sternberg and Janet Davidson, writing for Psychology Today, explained that solving puzzles requires a person to combine new data and old to form “novel ideas or solutions,” thereby exercising and strengthening the neural pathways.

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