What work can one never finish?

Can you make a fire with just a single stick?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?

There is a number which when you multiply by 3 and subtract 2 from the result, then the resulting number is the reverse of the actual number.

What is the smallest number that stands true on the statement?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

If you say my name, I will no longer exist. What am I?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?