Question

How many permutations can be made from the letters in the word "Wednesday" if a)4 letters are used at the same time b) all the letters are used

Attempt

a)$\displaystyle \frac{9!}{(9-4)!} = 3024 $

b) Since some letters are alike

$\displaystyle \frac{9!}{1!*2!*2!*1!*1!*1!*1!} =90720 $

Am I correct?