Combinations

In certain areas, such as probability or expanding a binomial expression, one needs to calculate the combination of n things taken k at a time, 0 £ k £ n. This is expressed by a variety of notations, including

           C(n,k)      nCk      nCr

This item calculates the number of different ways that k objects can be selected from a set of n objects. For example, in how may ways can we select 5 items from a set of 8 items? The answer is determined by calculating C(8,5). The item nCr( is found in the PROB (probability) menu.

Press 8,
press OPTN F6 F1 to access the PROB menu,
press 3 to select 3:nCr,

press 5 EXE to calculate C(8,5).

We observe that C(8,5) = 56.