Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

A man embarked on a questionnaire game. He kept asking the same question to whomever he found. The answer each time was different.

Can you guess what the question was?

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

Can you find the 09 errors in the picture below?