How is the moon similar to a dollar?

Move three sticks of the spiral below to form a square.

In a competitive exam, each correct answer could win you 10 points and each wrong answer could lose you 5 points. You sat in the exam and answered all the 20 questions, which were given in the exam.
When you checked the result, you scored 125 marks on the test.

Can you calculate how many answers given by you were wrong?

Rob is taller than Edwin, and Jurgen is shorter than Rob.
Of only one of the following statements, we now certainly know it is correct:

A.Edwin is taller than Jurgen
B.Jurgen is taller than Edwin
C.It cannot be determined if Jurgen or Edwin is the tallest.

A sundial has the fewest moving parts of any timepiece. Which has the most?

I am a three digit number.
My tens digit is five more than my ones digit.
My hundreds digit is eight less than my tens digit.
What number am I?

What has a bottom at the top?

You have a three-gallon and a five-gallon measuring device. You wish to measure out four gallons.

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?