Test your Riddle Skills, If you have two and need three, you’ll have four.

[Oday]

If you have three and need two you? If you have two and need three, you’ll have four.
If you have three and need two you will have one.
If you have one and need one you will have none.

WHAT AM I?

 

[Jeanette]

a negative number

(??)

u r going to post the answer, right?