## Brain Teaser

Question What is the side length of the outer regular pentagon? 3 1+3x 2+2x 2+3x Like these puzzles? Like these puzzles? For a lim

SolveQuestion What is the length of this infinitely-zig-zagging red line? 12 feet 15 feet 18 feet 30 feet It’s either infinite or und

SolveQuestion Every letter corresponds to a different digit and 0 cannot be the first digit of a number. What is the sum of C+A+R? 12 1

SolveQuestion A jar contains 8 cards numbered 1 through 8.You need a pair of them that sum to 9 but, unfortunately, you have to select

SolveQuestion How many triangles would balance three circles? 1 2 3 4 Like these puzzles? For a limited time, MIT alumni and friends ca

SolveQuestion Every angle in the figure is a right angle, and the colored rectangle has an area of 48. What is x? 10 10.5 11 11.5 Like

SolveQuestion You and three friends are sitting in a circle. Each of you holds in your hand 2 beans, each of which magically doubles ac

SolveQuestion If every letter corresponds to a different digit and E=5, what is Y? 3 4 7 8 Like these puzzles? For a limited time, MIT

SolveQuestion At the Mathematician’s Bicycle Shop, some of the bicycles have front wheels with larger diameter than the rear whee

SolveQuestion You have a pool table as shown shaped like an isosceles right triangle, with a ball that starts at the right angle. Where

SolveQuestion Two trains, each traveling at a speed of 50 km/h, are headed toward each other on the same track. At the exact moment the

SolveQuestion What is the measure of the missing angle? 10∘ 15∘ 20∘ 25∘ Like these puzzles? For a limited time, MIT alumni and

Solve