How many different numbers can be made using 4 numbers a b c and d and only + and - ?

Answer 1

Your question appears a bit too vague.

Are you allowing only 4 digit numbers, or can you have single, two-digit and three-digit numbers as well?
Can your variables a,b,c, or d take on the value of zero? That would drastically affect our solution.

Are you restricted to integers?? the form a/b is a number.

Please be more specific

Answer 2

How many different numbers can be made using 4 numbers a b c and d and only + and - ?

The number of arrangements of 4 different digits is 4! = 4x3x2x1 = 24.

The number of arrangements of the 4 colors is also 24.

Therefore, the number of arrangements of the 4 digits combined with the 4 colors is 24x24 = 576.