For each of the following expressions, write a factorial expression and then compute the value. Use the $_nC_r$ and $_nP_r$ functions on your calculator to make the computation.  

1. $_{10}P_8$ 

   Answer (a):

   $\frac{10!}{2!} = 1,814,400$

2. $_{10}C_8$ 

   Answer (b):

   $\frac{10!}{8!2!} = 45$

3. $_6C_1$ 

   Answer (c):

   $\frac{6!}{1!5!}$