Answer:
42
Explanation:
The permutation for that set of data looks like this:

The formula looks like this:

which of course simplifies to

which further simplifies down to the most basic simplification:

since the 5*4*3*2*1 that goes after the 6 in the numerator cancels with the 5*4*3*2*1 in the denominator.
You could also check this on your calculator. Hit "math", then arrow over to "Prob" and it's under nPr.