在根据标准找到其他单元号后划分单元号

Question

我有一个2000x20 excel文件。 B列中的每个单元格都有一个6位数字。当我在B列中有502000时，我感兴趣的是将单元格值M划分为B列501000的单元格值。除了B之外，行的其余部分从A到H是相同的。

现在我正在使用两个for循环，需要100秒才能完成。我正在寻找一个有效的想法。在此先感谢：）

Dim a As Integer, b As Integer

For a = Cells(Rows.Count, "A").End(xlUp).Row To 2 Step -1
    For b = a To 2 Step -1

        If Cells(a, "A") = Cells(b, "A") And Cells(a, "B") = "502000" _
           And Cells(b, "B") = "501000" And Cells(a, "C") = Cells(b, "C") _
           And Cells(a, "D") = Cells(b, "D") And Cells(a, "E") = Cells(b, "E") _ 
           And Cells(a, "F") = Cells(b, "F") And Cells(a, "G") = Cells(b, "G") _ 
           And Cells(a, "H") = Cells(b, "H") Then 
             Cells(a, "P") = Cells(a, "L") / Cells(b, "L")
        end if
    Next b
Next a