23
5*6*7*8=1680
5678 x 5678 = 32239684
5678 is only one 4-digit number. If you're willing to move the digits around to different positions, you can make 23 more.
56.78
5678*1 = 5678
Two make combinations you would take 2x1=2 combinations only
72% of 5678 = 5678/100 x 72 = 4088.16
9
Assuming you are using the standard English alphabet, the number of combinations you can make are: 26 x 26 = 676 combinations.
You could make 10*10*10*26*26*26 combinations, or 17576000 combinations.
8x7x6x5x4x3x2x1
5678 + 69022 = 74700