Question

Simplify the expression 12P5

Answer 1

We have a formula for this...
\[\Large _nP_r = \frac{n!}{(n-r)!}\]

But an easier way to think of it is, say, if we have 8P5

Just take 8 x 7 x 6 ... etc until you have exactly 5 factors.

do the same with 12P5

Answer 2

So 8P5 = 8x7x6x5x4 (we have 5 factors)
And this is equal to 6720