The letters P.O.S.S.E.S.S.E.S are shuffled and four selected and placed in a line.
How many possible selections are there of four letters.
I did it the long way by coming up with each case. For example,
case 1 - no 's'
case 2 - one 's'
S.P.O.E; S.P.E.E; S.O.E.E
case 3 - two 's'
S.S.P.E; S.S.E.E; S.S.O.E; S.S.P.O
case 4 - three 's'
S.S.S.E; S.S.S.P; S.S.S.O
case 5 - four 's'
This adds up to be 12.
Is there a better way to do this??
Since they are "placed in a line", I assume that their order is important.The letters of are shuffled.
Four are selected and placed in a line.
How many possible selections are there of four letters?
. . That is, we are spelling four-letter "words."
I see no way avoid a brute-force listing . . .
Now add them up . . .