Which Number is the odd one out?

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

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

Which is the smallest number that you can write using all the vowels exactly once?

Count the number of squares in the picture below.

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Our product and our sum always give the same answer. Who are we?

A man walked into a pub and went straight towards the Barman. He asked for a dirty martini from the Barman. The Barman thought something and then pulled out a pistol from his drawer and aimed it directly at the man. Why did he do that?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

How is the moon similar to a dollar?