How can you make number one disappear by adding something to it?

The king of Octopuses has servants who have six, seven or eight legs. The distinguishing characteristics of the servants is that the one with seven legs always lie but the one with either six or eight legs speak the truth always.

One day, four servants meet and converse:

The black one says, 'We have 28 legs altogether.'

The green one says, 'We have 27 legs altogether.'

The yellow one says, 'We have 26 legs altogether.'

The red one says, 'We have 25 legs altogether.'


Can you identify the colour of the servant who is speaking the truth?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

If we tell you that there is a relation between the numbers and letters in the given figure, can you analyze it and find the missing letter in the last box?

John and his team plan to rob a safe. They got just one chance to break the code else the local police will be informed. Below are clues:
A) Exactly one number is perfectly placed: 9 8 1
B) Everything is incorrect: 9 2 4
C) Two numbers are part of the code of the safe but are wrongly placed: 0 9 3
D) One number is part of the code of the safe but is wrongly placed: 1 4 7
E) One number is part of the code of the safe but is wrongly placed: 7 8 3

Why Aeroplane windows are round?

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 man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.

Can you find out the probability that he had taken out a pair of black socks ?

Replace the question mark with the correct number below.

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?