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excel – Custom SUMPRODUCT()

Posted by: admin May 14, 2020 Leave a comment

Questions:

I have the following table:

enter image description here

My objective is to spread out the 10,000 units across the 5 months, given the weightings below each month. The row adjacent the 10,000 is my best attempt at getting this (I have spent a few hours on this). The yellow is what I am after.

The logic I have tried to use to get the calculation is as follows: Calculate the even spread across the months (in this example 10,000 / 5 = 2,000 = X). Multiply each month weighting to get the weighted amount (in this example to get M2 = 1,600 and M4 = 3,000: X + (X * M2 weighting) etc). You can then take the total 10,000 minus the summation of these which will give you 5,400, which you can then distribute across the months don’t don’t have a weighting. There must be an easy way to do this with a SUMPRODUCT but I can’t seem to figure it out.

My best attempt so far is this:

=IF(B3=0,SUMPRODUCT(ABS((10000/5)*$B3:$F3)),(10000/5)+((10000/5)*B3))

How to&Answers:

Try the following:

enter image description here

Formula in B3:

=IF(B$2=0,($A3-SUMPRODUCT(($B2:$F2<>0)*(($A3/5)*(1+$B2:$F2))))/COUNTIF($B2:$F2,0),($A3/5)*(1+B$2))

Drag right.

Logic:

  • =IF(B$2=0,<true>,<false>) – Check if cell above equals zero
  • If above is false (so other than 0) then: ($A3/5)*(1+B$2) – First divide (10000/5) and multiply that outcome by (1-<percentage>)
  • If IF yields true – Check which cells in range are other than zero and multiply by the same logic as per step 2. The sum gained with SUMPRODUCT can then be deducted from 10000 and devided by the count of cells that actually do hold zero (hence the COUNTIF).