Get Free Riddles By Email!

Square Root Equations

Arrange the digits 1 through 9 into an equation so that the first number is the square root of the second number. (Two possible variations)

5672 = 321,489

OR

8542 = 729,316

Posted in Brain Teasers

Letter Missing From a Series

What letter is missing from this series?
B C D G P T V Z

The letter E. The series contains all of the letters that rhyme with bee (apologies to any English speakers who pronounce Z as zed instead of zee if this confused you).

Posted in Brain Teasers

Cheese Made Backwards

What cheese is made backwards?

Edam cheese.

Posted in Brain Teasers

Highest Product Using All Digits

What is the highest product that can be generated by multiplying two numbers while only using each digit once (1 through 9)?
For example, 12345678 * 9 = 111,111,102

9642 * 87531 = 843,973,902

Posted in Brain Teasers

One Three Five

What word comes next?

one three five four ______

Four. Each word is the number of letters in the previous word. And since four has four letters, it would continue with four forever after.

Posted in Brain Teasers

A Trapped Flock of Birds

A flock of birds are trapped in a delivery truck. When would the truck weigh the most?

a) When the birds are resting on the floor
b) When they’re all flying
c) The weight remains the same

c – The weight doesn’t change since it’s a closed system.

Posted in Brain Teasers

Characters In The Correct Order

Put the characters C D M L X in the correct order (not alphabetical).

X (10), L (50), C (100), D (500), M (1000). They’re Roman numerals in order from smallest to largest.

Posted in Brain Teasers

The Secret Lair

A secret lair has a code to only allow members to enter. The person wanting to enter says a random number, then is told a number in response. In order to enter they must say the correct third number. Here are sequences that allowed entrance.

1 3 5
27 11 6
9 4 4

What’s the third number of this series?

16 7 ?

Five because s-e-v-e-n has 5 letters. The first number can be anything, the second number is the number of letters in the first number, and the third number is the number of letters in the second number.

Posted in Brain Teasers

Copying Cassette Tapes

Joe and Andrea want to copy three 60-minute cassette tapes. They have a 2-cassette recorder to copy the tapes, allowing them to copy two tapes at a time. Each side takes 30 minutes to be copied, so two tapes can be copied in an hour and the third will take another hour. Andrea bets Joe she can copy all three tapes in 90 minutes. Does she win the bet?

In the first 30 minutes Andrea copies the A sides of tape 1 and 2.
In the second 30 minutes, she copies tape 1 side B and tape 3 side A (finishing Tape 1).
In the last 30 minutes, she copies tape 2 side B and tape 3 side B.

Posted in Brain Teasers

Paris to Roye

Hans made a meandering journey from Paris to Roye. On the first day, he went half of the distance. On the second day, he went one third of the remaining distance. On the third day he went three quarters of the remaining distance. The next day he traveled half of the remaining distance and was left with 5 kilometers to get to Roye. How far was the entire journey?

120 kilometers.

Hans’ trip went like this:

Day 1 – 60 km (60 km remaining)
Day 2 – 20 km (40 km remaining)
Day 3 – 30 km (10 km remaining)
Day 4 – 5 km (5 km remaining)
Day 5 – 5 km (arrives in Roye)

Posted in Brain Teasers