Using the value in a cell to reference the range of cells to use in a formula

[dannybten23]

Hi All,
This seems a bit hard to explain, but Ill do my best.
I want to write a formula that sums an array of cells. I want the array of cells to be based on the number I input in another cell. For example, I will have A1:A365 with values. I want A366 to sum the values starting at A1, and ending at A(the number that I enter in cell B2).
The attached example explains. I want the denominator in cell A366 to be the value in cell b1
Any ideas?
Thanks

[bebo021999]

So try:
=SUM($A$1:INDEX($A$1:$A$365,$B$1))
does it work?

[dannybten23]

Yes, that is what I needed. Thank you!

[arlu1201]

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