A combination is a selection of all or part of a set of objects, without regard to the order in which objects are selected.

If is a natural number and is a non-negative integer such that , then

i)

ii)

iii)

iv)

v)

vi) or

vii) If is an even natural number, then the greatest among is

If is odd natural number, then the greatest among is or

The number of ways of selecting items or objects from a group of distinct objects is