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Question
Find the number of words formed by permuting all the letters of the following words:
SERIES
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Solution
This word consists of 6 letters that include two Ss and two Es.
The total number of words is the number of arrangements of 6 things, of which 2 are similar to one kind and 2 are similar to the second kind.
⇒\[\frac{6!}{2!2!}\]= 180
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