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What is the sum of the first 121 numbers in Pascal's triangle.

supermanaccz  Oct 24, 2017
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 #1
avatar+317 
0

I got 2 to the 15 power but why?

supermanaccz  Oct 24, 2017
 #2
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The sum of rows 0 through n is = -1 + 2^(n + 1)=-1 + 2^(15+1) =65,535  ??  Just guessing !!

Guest Oct 24, 2017
 #3
avatar+78604 
+2

The 121st element will be the first number in the 16th row = 1 ...  [ I am letting the "1"  at the top of the triangle be the first row ]

 

The sum of the entries in any row will be  2^(r - 1)   where r is the row number

 

So....the sum of the first 121 elements will be 

 

16

Σ  2^(r - 1)  +  1   =   [ 65535 + 1 ]   =  65536

1

 

 

cool cool cool

CPhill  Oct 24, 2017

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