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I haven't touched VBA for Excel ever (this is seems a good start).

As for your formula: Is this an open formula where we pass * n* and

Usually this can be solved without do/for loops by doing the math (see for example here how math experts explain this - Scroll down to the explanation of Bikki Chhantyal).

But since you're asking specifically for loops, naturally you could use a for-loop as well ...

In pseudo code (so this is not real code and just illustrates the steps - since I am not familiar enough with VBA for Excel, so I'm basing this loosely what I remember from VBA in general):

Assuming an input of "x" and "n":

Public Function MyFormula(x As Integer, y As Integer)

MyFormula = 0

for Counter= 1 to n do

MyFormula = MyFormula + Counter*( x^( Counter-1 ) )

Next Counter

End Function

Again: this may not be 100% correct notation, I had to write this from memory from way back in the day.

You may need to modify it a little bit to make it work in VBA Excel.

So for your example n=10 (the picture you posted counts to 10), you'd call the function **MyFunction(x,10)**.

Note here:

if Counter=1 then the result will be 1 (as seen in your formula), no matter what X you entered, since X^0 = 1.

So in the code 1 * X^(1-1) = 1 * X^0 = 1 * 1 = **1**.

if Counter=2 then the result will be: 2 * X^(2-1) = 2 * X^1 = **2 * X**

if Counter=3 then the result will be: 3 * X^(3-1) = **3 * X^2**

etc.

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Basicly this is the thing that i have to turn into macro, have to use Do and For operators.

I have trouble finding out what should i put for limit.

Help would be highly appreaciated :)

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