NEED HELP ASAP WITH BIO/MATH QUESTION!!

Mmm

Are you asking how many ways can 4 elements be chosen from 56?  

(for this answer I have assumed order doesn count and each element can only be chosen once)

If so then the answer is

56C4

nCr(56,4) = 367290

nCr[56 + 4  - 1], 4 =59C4 =455,126

My understanding is that the 4 bases can be repeated, such as:AAAA, CCCC, GGGG and TTTT. The formula I used is the Binomial expansion with repeats allowed.

You could be right. I have a Math Dictionary and gives the following:
1-Combinations with repetitions: Each element can be chosen more than once for a particular combination. The number of possible combinations is then [n + r -1], r.
Example n=4, r=2  a, b, c, d: aa, ab, ac, ad,
                                                           bb, bc, bd,
                                                                   cc, cd,
                                                                        dd,
[4 + 2 -1], 2 =5C2 = 10