Originally Posted by

**wong93** I've done this before like months ago and now I forgot what these mean, so I need someone to explain to me what's going on lol

Question: How many different 4 letters words can be formed using letters of the word "MISSISSIPPI"

4 same --- 2 ways

3 same 1 different --- 2C1 X 3C1 X4!/3! <<I need someone to explain each of them to me ,3 of those ,if the other 3 at bottom are different ,please explain too thanks!

2 same 2 same --- 3C2 X4!/2!

2 same 1 diff 1 diff --- 3C1 X 3C2 4!/2!

1d 1d 1d 1d --- 4!

Total:176