# Permutations

• Jun 9th 2011, 05:58 AM
shayw
Permutations
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
• Jun 9th 2011, 06:04 AM
how far have you gone, show what you've tried please
• Jun 9th 2011, 06:10 AM
Plato
Quote:

Originally Posted by shayw
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

This is a vague question.
Do you mean that all eight symbols are use in each arrangement?
• Jun 9th 2011, 06:51 AM
shayw
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!
• Jun 9th 2011, 06:59 AM
Plato
Quote:

Originally Posted by shayw
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!