How many words can be formed from the letters of the word ‘SERIES’, which start with S and end with S?
To find: number of words which start and end with S
S | ………….. | ………….. | …………….. | …………….. | S |
There are 4 places to fill up with 4 letters out of which 2 are of the same kind
Number of words = 
12 words are possible
1