How many possible permutations are in letters a, b, c, d, e, f

What is the simplified form of (3.25x10^3)(7.8x10^6) written in scientific notation?

Hi, can anyone show me how to do this problem? 100 points for this. in advance

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document