You have eight letters
E1E2E3R1R2VMO. With the subscripts those are are distinct.
So with subscripts there are
8! ways to rearrange those eight letters.
The letters
E1E2E3 can be arranged in
3!=6 ways So if we simply remove the subscripts we have six identical strings.
There are
3!⋅2!8! ways to arrange the letters in
EVERMORE because there are three identical
E′s and two identical
R′s
Now please reply telling us why
(4!)2(2!)11! in the number of ways to rearrange the letters in
MISSISSIPPI.