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

John said, "If yesterday was tomorrow, today would be Friday."

When did John make this statement?

Why do you find that most of the buildings are deprived of the 13th floor?

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

There are six people in a family namely M, N, O, P, Q and R.

R and O are brother and sister.

N is the brother of Q's husband.
P is the father of M and grandfather of R.

How many male members are in the family?

What are the next two letters in the following series and why?
W A T N T L I T F S _ _

*Hint: Check Puzzle Title

Which is the correct shadow of the bird?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)