Can you get to 10 from the numbers 1, 1, 5, 8? You have to use all the numbers, and you have to each number exactly once. You can use + - ÷ × and parentheses ().

You are not allowed to use exponents, so 10 = 8 + 1 + 1^5 is not a valid solution.

This problem went viral when Google Japan used it in a commercial for Nexus 7: https://www.youtube.com/watch?v=JslkN8IulNA

List of all possible combinations (Google spreadsheet): https://docs.google.com/spread....sheets/d/1ijZi0xyF2A

Blog post (explanation of computation): http://mindyourdecisions.com/b....log/2015/09/19/viral

I found the problem via:
http://wordplay.blogs.nytimes.....com/2015/09/07/24/?_
http://7puzzleblog.com/209/

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My Books

"The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 4/5 stars on 23 reviews) https://www.amazon.com/gp/product/1500497444

"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 5/5 stars on 1 review) https://www.amazon.com/gp/product/1523231467/

"Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.5/5 stars on 11 reviews. https://www.amazon.com/gp/product/1517421624/

"Math Puzzles Volume 2" is a sequel book with more great problems. https://www.amazon.com/gp/product/1517531624/

"Math Puzzles Volume 3" is the third in the series. https://www.amazon.com/gp/product/1517596351/

"40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.9/5 stars on 7 reviews) https://www.amazon.com/gp/product/1517319307/

"The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 3 reviews) https://www.amazon.com/gp/product/150779651X/

"Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 1 review) https://www.amazon.com/gp/product/1500866148/