<PRE><B>Question 333411</B>
while the word MATHEMATICS has 11 words, there are really only 8 unique words
M, A and T are duplicated.
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So, your problem becomes number of arrangements of 4 letters from a word of 8 unique letters
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there are 8 choices for the first word
there are then 7 choices for the second word
after that there are 6 choices for the third word
and finally there are 5 choices for the fourth word

8*7*6*5=1680</PRE>