Counting Consecutive Negative Numbers

Lori has a series of numbers, in adjacent cells, that can be either positive or negative. She would like a way to determine the largest sequence of negative numbers in the range. Thus, if there were seven negative numbers in a row in this sequence, she would like a formula that would return the value 7.

We've looked high and low and can't find a single formula that will do what is wanted. You can, however, do it with an intermediate column. For instance, if you have your numbers in column A (beginning in A1), then you could put the following formula in cell B1:

=IF(A1<0,1,0)

Then, in cell B2 enter the following:

=IF(A2<0,B1+1,0)

Copy this down to all the other cells in column B for which there is a value in column A. Then, in a different cell (perhaps cell C1) you can put the following formula:

=MAX(B:B)

This value will represent the largest number of consecutive negative values in column A.

If you don't want to create an intermediate column to get the answer, you could create a user-defined function that will return the value.

Function MaxNegSequence(rng As Range)
' search for the largest sequence
' of negative numbers in the range

    Dim c As Range
    Dim lCounter As Long
    Dim lMaxCount As Long
 
    Application.Volatile
    lCounter = 0
    lMaxCount = 0
    On Error Resume Next
    For Each c In rng.Cells
        If c.Value < 0 Then
            lCounter = lCounter + 1
            If lCounter > lMaxCount Then
                lMaxCount = lCounter
            End If
        Else
            lCounter = 0
        End If
    Next c
 
    MaxNegSequence = lMaxCount
End Function

To use the function, just place a formula similar to the following in your worksheet:

= MaxNegSequence(A1:A512)

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (3533) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Counting Consecutive Negative Numbers.