Math Riddles

These Math Riddles are based on math concepts and can be solved with a bit of math and logic. These fun riddles can surely give you a tough time.

King-size Conundrum

A medieval king needed to work out how he could recruit fighting men for the battle ahead. However, there were so many distractions around the castle, his thinking became confused. So in order to change his daze into knights, he asked for a secluded walk to be made so he could ponder in peace.

The head gardener was given the job of planting lines of high bushes. First, he planted a line running 100 paces east. Then from the end of that line he planted a line 100 paces north, then 100 west, 98 south, 98 east, 96 north, 96 west, and so on. This made a square spiral path 2 paces wide.

If the king intended to walk down the middle of the path, how long was the path?

Riddle Answer

3 Ants on Vertices of Triangle

Suppose that you have a triangle with 3 ants on different vertices (corners) of the triangle. What is the probability that either 2 of the ants or all of the ants collide if all 3 ants start walking on the sides of the triangle?

Riddle Answer

The Mongolian Postal Service

The Mongolian Postal Service has a strict rule stating that items sent through the post must not be more than 1 meter long. Longer items must be sent by private carriers, and they are notorious for their expense, inefficiency, and high rate of loss of goods.

Boris was desperate to send his valuable and ancient flute safely through the post. Unfortunately, it was 1.4 meters long and could not be disassembled as it was one long hollow piece of ebony. Eventually he hit on a way to send it through the Mongolian Postal Service. What did Boris do?

Riddle Answer

Nine Lottery Balls

Ali and Zoe reach into a bag that they know contains nine lottery balls numbered 1 to 9. They each take one ball out to keep and they look at it secretly. Then, they make the following statements, in order:

Ali: I don’t know whose number is bigger.
Zoe: I don’t know whose number is bigger either.
Ali: I still don’t know whose number is bigger.
Zoe: Now I know that my number is bigger!

Assuming Ali and Zoe are perfect logicians, what is Zoe’s smallest possible number?

Riddle Answer

Kids in the Class

14 of the kids in the class are girls. 8 of the kids wear blue shirts. 2 of the kids are neither girls nor wear a blue shirt.

If 5 of the kids are girls who wear blue shirts, how many kids are in the class?

Riddle Answer

Math Riddles

King-size Conundrum

3 Ants on Vertices of Triangle

The Mongolian Postal Service

Nine Lottery Balls

Kids in the Class

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