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

What you cannot hold but it is yours?

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Can you count the number of quadrilaterals in the picture below?

Doctor Alex and a bus driver John are both in love with the same woman named Olivia. The bus driver need to go for a long trip of 10 days, Before he left he gave Olivia 10 apples.

There are two dice with empty faces in front of you and a marker. You can mark any number on each of the faces of the two dice, but you have to display all 31 days of the month using the two of them.

Which numbers will you mark on which dice so that you can easily depict all the dates of the month?

Which Number is the odd one out?

A) 7145
B) 2716
C) 5321
D) 4135

Count the number of squares in the picture below.