Combinations in Maths
Posted by
Ravi Kumar at Friday, August 28, 2009
Share this post:

Combinations:
Each of different groups or selections which can be formed by
taking some or all of a number of objects,is called a combination.
eg: Suppose we want to select two out of three boys A,B,C .
then ,possible selection are AB,BC & CA.
Note that AB and BA represent the same selection.
Number of Combination:
The number of all combination of n things taken r at a time is:
nCr = n! / (r!)(nr)!
= n(n1)(n2). . . . . . . tor factors / r!
Note: nCn = 1 and nC0 =1
An Important Result:
nCr = nC(nr)
For problems click Here.