Math Help - Permutations

1. Permutations

Hi

For this question: how many different arrangements of the letters of the word SERIES are possible if no two vowels are together. I keep on getting 36 instead of 18

My working out is:

Consonants can be arranged in 3!/2! ways (X X X) so vowels can be allocated between any of the 4 spaces available i.e. (4 * 3* 2)/2!

What am I missing out??

Thanks

2. You are missing that there are two s's.

3. Havent I accounted for that by dividing by 2! for the consonants part?

4. I read too quickly. You are correct. I also get 36.