You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

What kind of band never plays music?

If 2 workers can complete painting 2 walls in exactly 2 hours.

How many workers would be needed to paint 18 walls in 6 hours?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?

I have branches, but no fruit, trunk or leaves. What am I?

What does the below image rebus riddle means ?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?