SUMPRODUCT in Paginated Report using MS Report Builder

Hi,Anonymous .I am glad to help you.
In Power BI Desktop, you can easily calculate results with DAX, while in Power BI Report Builder, creating a custom method would be a good option.
Maybe you could try :

Public Function CalculateSumProduct(ByVal startFTP As Double(), ByVal previousBalance As Double()) As Double
    Dim sumProduct As Double = 0
    For i As Integer = 0 To startFTP.Length - 1
        sumProduct += startFTP(i) * previousBalance(i)
    Next
    Return sumProduct
End Function


=Code.CalculateSumProduct(Fields!StartFTP.Value, Fields!PreviousBalance.Value) / Sum(Fields!PreviousBalance.Value)

Custom code in expressions in a paginated report in Power BI Report Builder - Power BI | Microsoft Learn

I hope my suggestions give you good ideas, if you have any more questions, please clarify in a follow-up reply.
Best Regards,
Carson Jian,
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