**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*)
* _{n}*C

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.

Press8,

pressOPTN F6 F1to access thePROBmenu,

press3to select3:nCr,press

5 EXEto calculate C(8,5).

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