How many three-letter sequences can be made from the letters in the word FORESAW?

1 Answer




We have 7 letters and we're going to grab 3 at a time to make a word. The order that we pick the 3 letters is important - WAS is different than SAW. And so we use the permutation calculation, the general formula is:

#P_(n,k)=(n!)/((n-k)!); n="population", k="picks"#


We can evaluate in a couple of different ways - one is by using a factorial table:


and the other is by breaking down the multiplication:


Either way, we arrive at 210