Hello and thank you for your question.
Here's the 'brute force' answer: six
bo ob
by yb
oy yo
Technically, this is an example of a "Permutation of less than all,"
that is, number of permutations of 3 different things taken 2 at a
time.
This is usually symbolized as 3P2, or 3!/(2-1)! or (3*2*1)/1 = 6
Here is how Dr. Math explains it (Dr. Math uses CAT as the test word)
"For our CAT example, we have:
3! 3 x 2 x 1
3_P_2 = ---- = ----------- = 6
1! 1
We can use any one of the three letters in CAT as the first member of
a permutation. There are three choices for the first letter: C, A, or
T. After we've chosen one of these, only two choices remain for the
second letter. To find the number of permutations we multiply: 3 x 2 =
6.
Note: What's a factorial? A factorial is written using an exclamation
point - for example, 10 factorial is written 10! - and means multiply
10 times 9 times 8 times 7... all the way down to 1."
http://www.mathforum.com/dr.math/faq/faq.comb.perm.html
Search terms used:
permutation word letters order
That's it!
Google Answers Researcher
Richard.ga |