Turn monthly column data into Quarterly based on Date

[smartpat19]

Look up date and return the cell and the prior two columns (three columns total)

Data field:

1/1/2019	2/1/2019	3/1/2019
10	10	10

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Summary:

3/1/2019

30 (formula)

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Thank you

 

[Joe4]

I set up a simple example where the dates are in row 1, and the corresponding values are in row 2.
Then, if the value we want to look up is in cell F3, I put this formula in G3 to get my result:

=INDEX(2:2,0,MATCH(F3,1:1,0))+IFERROR(INDEX(2:2,0,MATCH(F3,1:1,0)-1),0)+IFERROR(INDEX(2:2,0,MATCH(F3,1:1,0)-2),0)