Logic puzzles, riddles, & maths problems

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Can you solve this simple-looking arithmetic challenge?

If I scramble a Rubik's cube for long enough, will it solve itself?

Can you solve this little minesweeper puzzle?

It's night time and 4 friends need to cross a fragile bridge, but they only have one torch. What's the order in which they should cross?

Three friends are given three different numbers that add up to a dozen. Can you figure out everyone's numbers?

You have two magical ropes that you can set on fire and you need to count 45 minutes. How do you do it?

You are on vacation and must find the most efficient way to cross all bridges. How will you do that?

Alice and Bob sit across each other, ready for their game of coins. Who will emerge victorious?

Can you find a really large triangle that is also really tiny?

This is an algorithmic puzzle where you just have to turn some coins.

Two doors, one gives you eternal happiness and the other eternal sadness. How can you pick the correct one?

Syncro is a beautiful game where you have to unite all the petals in a single flower. In how many moves can you do it?

A waiter at a restaurant gets a group's order completely wrong. Can you turn the table to get two or more orders right?

A bunch of ants are left inside a very, very, tight tube, and they keep colliding with each other and turning around. How long will it take them to escape?

You are sunbathing when you decide to go and talk to some friends under a nearby sun umbrella, but first you want to get your feet wet in the water. What is the most efficient way to do this?

This problem is a step up from Problem #028 - hidden key. Can you tackle this one?

There is a key hidden in one of three boxes and each box has a coin on top of it. Can you use the coins to let your friend know where the key is hiding?

Five sailors and their monkey were washed ashore on a desert island. They decide to go get coconuts that they pile up. During the night, each of the sailors, suspicious the others wouldn't behave fairly, went to the pile of coconuts take their fair share. How many coconuts were there in the beginning..?

I bet you have seen one of those Facebook publications where you have a grid and you have to count the number of squares the grid contains, and then you jump to the comment section and virtually no one agrees on what the correct answer should be... Let's settle this once and for all!

Some people are standing quiet in a line, each person with a hat that has one of two colours. How many people can guess their colour correctly?