Please Note: This article is written for users of the following Microsoft Excel versions: 2007, 2010, and 2013. If you are using an earlier version (Excel 2003 or earlier), this tip may not work for you. For a version of this tip written specifically for earlier versions of Excel, click here: Finding the Number of Significant Digits.

Finding the Number of Significant Digits

by Allen Wyatt
(last updated July 12, 2014)

1

Brenda is interested in knowing the number of significant digits in a value. She wonders if there is an Excel function or formula she can use that would return the number of significant digits in the value shown in a cell.

This question is not as simple as it seems. For some people, finding the number of digits in a value, less any decimal points or negative signs. If that is all you need, then something like this formula will work just fine:

=IF(A1<0,IF(A1=INT(A1),LEN(A1)-1,LEN(A1)-2),IF(INT(A1)=A1,LEN(A1),LEN(A1)-1))

The reason that this isn't that simple, however, is because what constitutes the number of significant digits in a value depends on many things. The bottom line is that you can't always tell by looking at a value how many significant digits it has.

For instance, the value 100 could have 1, 2, or 3 significant digits. It is presumed that the value 1.00 has 3 significant digits, but that may not be the case if the value displayed is the result of formatting imposed by Excel—for instance, the value in the cell could be 1.0000437, which Excel formats as 1.00. You can discover more about the topic of significant digits here:

http://excel.tips.net/T012083

There are some generally accepted ways to identify significant digits in a number, but any attempt to codify a set of rules is always open to debate. One such set of rules has been noted at Wikipedia, in the "Identifying Significant Digits" section of this article:

http://en.wikipedia.org/wiki/Significant_figures

With at least a rudimentary set of rules in mind (such as the one in the Wikipedia article) it is possible to develop a user-defined function that will give you the most likely number of significant digits for a value.

Function SigFigs(rng As Range, Optional iType As Integer = 1)
    'iType = 1 is Min
    'iType = 2 is Max

    Dim rCell As Range
    Dim sText As String
    Dim sText2 As String
    Dim iMax As Integer
    Dim iMin As Integer
    Dim iDec As Integer
    Dim i As Integer

    Application.Volatile
    Set rCell = rng.Cells(1)

    'if not a number then error
    If Not IsNumeric(rCell) Or IsDate(rCell) Then
        SigFigs = CVErr(xlErrNum)
        Exit Function
    End If

    sText2 = Trim(rCell.Text)
    sText = ""
    'find position of decimal point (it matters)
    iDec = InStr(sText2, ".")

    'strip out any non-numbers (including decimal point)
    For i = 1 To Len(sText2)
      If Mid(sText2, i, 1) >= "0" And _
        Mid(sText2, i, 1) <= "9" Then _
        sText = sText & Mid(sText2, i, 1)
    Next

    'remove any leading zeroes (they don't matter)
    While Left(sText, 1) = "0"
        sText = Mid(sText, 2)
    Wend
    iMax = Len(sText)

    'strip trailing zeroes (they don't matter if no decimal point)
    sText2 = sText
    If iDec = 0 Then
        While Right(sText2, 1) = "0"
            sText2 = Left(sText2, Len(sText2) - 1)
        Wend
    End If
    iMin = Len(sText2)

    'return Min or Max
    Select Case iType
        Case 1
            SigFigs = iMin
        Case 2
            SigFigs = iMax
        Case Else
            SigFigs = CVErr(xlErrNum)
    End Select
End Function

You call this function by using the following in your worksheet:

=SigFigs(A1, x)

You can replace x with either 1 or 2. If you specify 1, then the function returns the minimum number of significant digits. If you specify 2, then the function returns the maximum number of significant digits. In most cases the two possible return values will be the same, except with values that are whole numbers, without a trailing decimal point, that have trailing zeroes. In other words, if you use the function to evaluate the number 1234000, then the minimum (x is 1) returns 4 and the maximum (x is 2) returns 7.

The function takes into consideration how the number appears in the worksheet, meaning that it matters how the number is formatted. It strips out any formatting characters, such as negative signs, parentheses, and commas.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (10976) applies to Microsoft Excel 2007, 2010, and 2013. You can find a version of this tip for the older menu interface of Excel here: Finding the Number of Significant Digits.

Author Bio

Allen Wyatt

With more than 50 non-fiction books and numerous magazine articles to his credit, Allen Wyatt is an internationally recognized author. He  is president of Sharon Parq Associates, a computer and publishing services company. ...

MORE FROM ALLEN

Reordering the Display of a Data Series

Once you create a chart, you aren't limited to keeping the data series in the order they originally appeared. You can shift ...

Discover More

Providing Helpful Tips for Easy AutoText Entry

Can't figure out why you can't see your AutoComplete tips that you are used to seeing? The reason is because Word has done ...

Discover More

Changing Label Printing Order

If you want to change the order in which labels are printed when doing a mail merge, Word doesn't provide many options. This ...

Discover More

Solve Real Business Problems Master business modeling and analysis techniques with Excel and transform data into bottom-line results. This hands-on, scenario-focused guide shows you how to use the latest Excel tools to integrate data from multiple tables. Check out Microsoft Excel 2013 Data Analysis and Business Modeling today!

More ExcelTips (ribbon)

Restoring the Analysis ToolPak

Add-ins for Excel, such as the Analysis ToolPak, are stored in files on your hard drive that can be deleted. If you delete ...

Discover More

A Shortcut for Switching Focus

While not technically an Excel-only tip, the shortcuts described in this tip will help you switch focus from your workbook to ...

Discover More

Tasks for Each Workbook

Excel allows you to control how it uses the Windows Taskbar. This tip explains the two ways Excel can use the Taskbar and how ...

Discover More
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

View most recent newsletter.

Comments

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is 8 - 2?

2015-08-29 07:25:38

Arun Kumar

Hi,

I hope there is an easy way out.

=LEN(A1)-LEN(SUBSTITUTE(A1,"Digit",""))

This formula basically counts the original length of the cell, replaces the desired number by null and gets the length again, finally reduces the new length from the original length and you get your number of instances of a specified digit.

Regards, Arun


This Site

Got a version of Excel that uses the ribbon interface (Excel 2007 or later)? This site is for you! If you use an earlier version of Excel, visit our ExcelTips site focusing on the menu interface.

Newest Tips
Subscribe

FREE SERVICE: Get tips like this every week in ExcelTips, a free productivity newsletter. Enter your address and click "Subscribe."

(Your e-mail address is not shared with anyone, ever.)

View the most recent newsletter.