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A)2 B)799 C)159600 D)63520800

 Jan 28, 2015

Best Answer 

 #1
avatar+128053 
+5

This looks difficult...but it's not.....

Notice  that  400! / 398!  =  (400 x 399 x 398 x 397.......) / (398 x 397 x 396 x 395...)

All all the terms on the "top" cancel with all the terms on the "bottom" except 400 x 399

Can you take it from here??

 

 Jan 28, 2015
 #1
avatar+128053 
+5
Best Answer

This looks difficult...but it's not.....

Notice  that  400! / 398!  =  (400 x 399 x 398 x 397.......) / (398 x 397 x 396 x 395...)

All all the terms on the "top" cancel with all the terms on the "bottom" except 400 x 399

Can you take it from here??

 

CPhill Jan 28, 2015
 #2
avatar
0

The answer is 159600 right? thanks for the help!!!

 Jan 28, 2015
 #3
avatar+128053 
0

Yep....that's it !!!

 

 Jan 28, 2015

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