Question 1029840
 
Question:
How many ways can the letters in the word AGATHIST be rearranged?
Any help will be appreciated!
 
Solution:

the number of permutations is given by 
n!/(n1!n2!n3!...nk!)
where each of n1, n2... is the number of occurrences of each letter.
Making a count of each letter:
A 2
G 1
H 1
I 1
S 1
T 2
total 8.
So the number of permutations is
8!/(2!1!1!1!1!2!)=40320/4=10080
 
The same formula can also be used to solve problems of permutation of multiple coloured balls.