Which perfect square of a 4-digit number has the same last four digits as the original number?Continue reading “Four Digits Squared”
A bicycle shop has some unique bicycles. Each bike is identical, and each bike’s front and back wheels has at least one spoke each. You don’t know how many bicycles are in the shop, but you know there are between 200 and 300 spokes in total.
If you knew the exact number of spokes, you would be able to figure out the number of bicycles.
You don’t know the exact number of spokes, but just knowing the fact that you would be able to figure it out with that information allows you to deduce the answer. How many bicycles and spokes are there?Continue reading “Deducing Bicycle Spokes”
Which two-digit numbers are exactly equal to seven times the sum of its digits?Continue reading “Seven Times the Sum of Its Digits”
There are 100 face-down cards. The first person that passes by flips over every card, the 2nd person that passes by flips over every 2nd card, and so forth – the n-th person that passes by flips over every n-th card. Before you know it, 100 people have passed by.
After all 100 people have passed by, which cards are face-up and which are face-down?
Fun fact, this was an actual brainteaser given to me in the first round interview for a hedge fund internship back in 2011.
Preparing for a brain teaser interview? Check out our ultimate guide to brain teaser interviews.Continue reading “Flipping Every N-th”