Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

Can you count the number of squares in the figure below?

What does it mean?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

When is the top of a mountain similar to a savings account?

Pronounced as 1 letter, And written with 3, 2 letters there are, and 2 only in me. I’m double, I’m single, I’m black blue and grey, I’m read from both ends, and the same either way. What am I?

A man was driving a black truck. His lights were not on. The moon was not out. A lady was crossing the street. How did the man see her?

Replace the question mark in the picture below.

What is at the end of a rainbow?