Hi every one
I have ABCDEF++/-
how to calculate number of permutations when the first and second element
must begin with a letter and also we can use a letter one time in each permutation
thanks
Sorry didn't explain clearly
I have 11 symbols (6 letters ABCDEF and +-*/^)
in each arrangement i use the 11 symbols but the first and second symbol must begin with a letter
eg AB+-CD*/EF^
so i try this
for 9 symbols i have 9! and for the for the first and second symbol 6*5
so 6*5 * 9!