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what is the permutations of the letters in the word of ASSASSIN?
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The original formulation in the post is INCORRECT.
The correct formulation is THIS :
What is the number of all distinguishable arrangements of the letters in the word ASSASSIN ?
SOLUTION
The given word has 8 symbols.
Of these 8 symbols, the letter "A" repeats 2 times, and the letter "S" repeats 4 times.
All other letters are distinct and unique.
The number of all permutations of 8 symbols is 8!
But the number of all distinguishable arrangements is
8!/(2!*4!) =
= 840. ANSWER
In the formula, 2! in the denominator stands to account for repeating letter "A",
while 4! in the denominator stands to account for repeating letter "S".