Another question from **O Level Additional Mathematics (A-Math)**.

lijun(: said...

hey. i just want to clarify something that i'm not very sure of.

is nCr x r! = nPr ??

By definition,

nCr = nPr/r!

Well, I never remember this 'rule'

For example, find the number of ways to form a 3 letter word from a,b,c,d,e

Student #1:

5C1*4C1*3C1

Student #2:

5P3

Both answers are correct though different approaches are taken, so no need to remember the 'rule'

:)