Sum_from_ i=1_to_N A^i?

  • Thread starter Thread starter Mike
  • Start date Start date
M

Mike

Hi,

Say I have data A in column C, and integer data N in column B. In
column E, I want to perform

Sum_from_i=1_to_N A^N?

How does the SUM_From_To is applied in a cell?

Thanks
 
My reading of this is: In Cells B1:D2 to have
N A Sum of powers
4 3 120
Your aim is find the sum of: 3^1 + 3^2 + 3^3 + 3^4
In D2 enter =SUMPRODUCT(C2^(ROW(INDIRECT("1:"&B2))))
Hope I read you correctly
best wishes
 
My reading of this is: In Cells B1:D2 to have
N       A     Sum of powers
4       3      120
Your aim is find the sum of: 3^1 + 3^2 + 3^3 + 3^4
In D2 enter =SUMPRODUCT(C2^(ROW(INDIRECT("1:"&B2))))
Hope I read you correctly
best wishes
--
Bernard Liengme
Microsoft Excel MVPhttp://people.stfx.ca/bliengme










- Show quoted text -
Click to expand...

Yes, thanks Bernard
 
You can allso compute it directly using:

Sum{i=1 to N}(A^i) = ( (A^(N+1) - 1) / (A - 1)) -1 for A <> 1

-Nick
 
My reading of this is: In Cells B1:D2 to have
N A Sum of powers
4 3 120
Your aim is find the sum of: 3^1 + 3^2 + 3^3 + 3^4
In D2 enter =SUMPRODUCT(C2^(ROW(INDIRECT("1:"&B2))))
Hope I read you correctly
best wishes
Click to expand...

Hi. Just to give an alternative...

a=3
n=4
? -1-FV(a-1,n,1,1,0)
120

A quick visual check using 10 ^ i

{10,100,1000,10000,100000}

Visually, the sum is just 111,110

a=10
n=5
? -1-FV(a-1,n,1,1,0)
111110


= = = = = = =
HTH :>)
Dana DeLouis
 
Nice, Dana!
As a chemist, finance function are not the first thing I grab for!
best wishes
Bernard
 
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