Formula for adding different length columns

Good Morning, I'm trying to come up with a formula to look at for example different year by weeks, for example how many units were sold in the first week of 2018 as against 2017.

Column A (Number of weeks) Column B Sales for each week in 2018, Column C sales for each week in 2017 (and so on).

Now I can obviously have row after row with number of weeks but is there a way that whatever number I place in column A, cell A1, it will read down that many rows in column B, C (and so on)

Thanks for any help

Will you please attach a SMALL sample Excel workbook (10-20 rows of data is usually enough)? Please don't attach a picture of one (no-one will want to re-type all your stuff before starting).

1. Make sure that your sample data are truly REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired solution is also shown (mock up the results manually).

3. Make sure that all confidential information is removed first!!

4. Try to avoid using merged cells. They cause lots of problems!

Unfortunately the attachment icon doesn't work at the moment. So, to attach an Excel file you have to do the following: Just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Easier to follow!!

=SUM(B1:INDEX($B$1:$B$20,A1))

No it doesn't, but it does need an addition, to take account of the case where G2 is blank


=IF(G2="","",SUM(H3165:INDEX($H$3165:$H$3227,G2)))

Beware of OFFSET. It recalculates EVERY TIME any change is made in your workbook. This can cause performance issues.