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![[Post New]](/templates/default/images/icon_minipost_new.gif) 30 Nov 2007 10:06:59 IST
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i got a formula for such problems in one of our books
the number of permutations of n different things taken r at a time in which x particular things always occur in assigned order is n-xP r-x (r-x+1)
in the given question, we have to permutate 5 letters taking 5 at a time(i.e, all at a time) in which 2 things always occur at the same order. so puttinh them in formula,
no of reqd permutations= 5-2P 5-2 (5-2+1)= 24
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it is not important where u stand, but in which direction u are moving |
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