10+10 and 11+11 can give you the same answer.

Explain how?

John is selling fruits.
He sells grapes at $30, Dates $25, and a Wolfberry $45.
At what price does he sell fig?

PS: Logical Thinking

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

When can we add 2 to 11 and get 1 as the correct answer?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

What has to be broken before you can use it?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

Look at the picture and find out which square is not linked with any of the other squares.