Puzzles & Quizzes

Can You Solve the 7-Cent Logic Puzzle?

Can you solve the seven-cent logic puzzle? This problem doesn't require math — instead, it's is easiest to solve by experimenting with a drawn diagram and seven actual coins. Check it out below and see if you can crack it.

Here's the Puzzle

You have a diagram with eight vacant circles, all arranged in a circle and connected by lines. Specifically, two lines each: the first line connects any given circle to the fourth circle to its left, the second line connects that circle to the fourth circle to its right.

You must place a coin on a vacant spot in the diagram and slide it along a line to another vacant spot. Do this with each coin until all but one of the spots are filled. Can you place and move all seven coins so that each one lands in a vacant circle and moves to another?

Watch the video below or scroll down for the solution.

Here's the Solution

The key to this puzzle is in the way you visualize the larger circle. If you follow your finger along the connecting lines, you can see that they take you to every vacant circle in sequence, only taking you back to where you started after you've hit every circle. You can use that path in your strategy.

To solve this puzzle, place your first coin in any circle and move it along either line to the next connected circle. Now you want your next coin to stop where your first coin started, and that means you only have two placement options: one of the two circles that connects to the circle you first placed the previous coin in. Then you can move your second coin to that circle. Continue in this manner, working backward from the first circle in which you placed the previous coin so that the next coin lands there, until you've used all seven coins. Did you figure it out?

Get stories like this one in your inbox or your headphones: Sign up for our daily email and subscribe to the Curiosity Daily podcast.

For more wild puzzles, check out "Scam School: Your Guide to Scoring Free Drinks, Doing Magic & Becoming the Life of the Party" by Brian Brushwood. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Curiosity Staff January 21, 2016

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.