If eleven plus two equals one, what does nine plus five equal?

You are playing as white and given four rooks to checkmate the black king in four moves with the following rules 1. You can place one rook every move and ensure the black king should be in check position.2. After four moves the black king should be in the checkmate position.

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

There was a blind beggar living on the footpath of a street. Suddenly one day, the beggar's brother died. What was the relation of the blind beggar with the person who died?

PS: Brother is not the answer.

A bag contains 64 balls of eight different colours. There are eight of each colour (including red). What is the least number you would have to pick, without looking, to be sure of selecting 3 red balls?

Which is Odd One Out and why?

4377

3954

9862

8454

9831

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

What has one eye, but can’t see?

What does this rebus puzzle mean?