A permutation is an ordering, a re-arrangement of symbols or objects. Here we calculate the number of arrangements possible given n symbols, with k of these being used in each arrangement. Again we expect to see some large values, and so also report results as base-2 logs or bits.
A combination is a particular set of symbols, independent of their ordering or arrangment. Here we calculate the number of combinations of n things taken k at a time. Again we also report results as base-2 logs or bits.