**Please Note: **
This article is written for users of the following Microsoft Excel versions: 2007, 2010, 2013, 2016, 2019, and Excel in Microsoft 365. 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: Playing with a Full Deck.

Written by Allen Wyatt (last updated November 23, 2022)**This tip applies to** Excel 2007, 2010, 2013, 2016, 2019, and Excel in Microsoft 365

Excel is great at generating random numbers, but it is less great at filling a range of cells with random numbers in which no particular number is repeated twice. For instance, you might want to populate 52 cells with the numbers 1 through 52, in random order. (This is very similar to choosing cards from a deck in random order, where a particular card can only be chosen once. Thus, the title for this tip.)

There obviously is no built-in Excel function to provide this capability, so you are left to work with macros. Fortunately, such a macro is not terribly difficult to create. The following macro will do the trick nicely:

Sub FillRand() Dim nums() As Integer Dim maxval As Integer Dim nrows As Integer, ncols As Integer Dim j As Integer, k As Integer Dim Ptr As Integer Randomize Set s = Selection maxval = s.Cells.Count nrows = s.Rows.Count ncols = s.Columns.Count ReDim nums(maxval, 2) 'Fill the initial array For j = 1 To maxval nums(j, 1) = j nums(j, 2) = Int((Rnd * maxval) + 1) Next j 'Sort the array based on the random numbers For j = 1 To maxval - 1 Ptr = j For k = j + 1 To maxval If nums(Ptr, 2) > nums(k, 2) Then Ptr = k Next k If Ptr <> j Then k = nums(Ptr, 1) nums(Ptr, 1) = nums(j, 1) nums(j, 1) = k k = nums(Ptr, 2) nums(Ptr, 2) = nums(j, 2) nums(j, 2) = k End If Next j 'Fill in the cells Ptr = 0 For j = 1 To nrows For k = 1 To ncols Ptr = Ptr + 1 s.Cells(j, k) = nums(Ptr, 1) Next k Next j End Sub

This macro uses a two-dimensional array (nums) to figure out which numbers to use and the order in which they should be used. Near the beginning of the macro the array is filled with a static number (1 through the number of cells) and a random number between 1 and the number of cells. This second number is then used to sort the array. Once the array is stored, it is a simple matter to place the original numbers in the cells.

By the way, the reason a two-dimensional array is used is because the Rnd function that VBA uses to generate random numbers can return duplicate values. Thus, even though the second dimension of the array can have duplicates in it, when the array is finally sorted, the first dimension will not have duplicates.

To use the macro, start by selecting the cells you want to have filled with sequential values in a random order. When you run the macro, that range is filled. For instance, if you select ten cells and then run the macro, then those cells are filled with the numbers 1 through 10, in random order.

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This tip (8269) applies to Microsoft Excel 2007, 2010, 2013, 2016, 2019, and Excel in Microsoft 365. You can find a version of this tip for the older menu interface of Excel here: **Playing with a Full Deck**.

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2022-11-25 01:45:13

Tomek

1. Create two columns with headings labelled random and unique.

2.In the first column select as many cells as you want unique numbers. Enter the formula: =RAND(). Press Ctrl+ENTER. This will populate all selected cells with this formula.

3. Fill the second column with sequential numbers from 1 to whatever is needed to have both columns of the same length.

4. (Optional but convenient) Convert the two-column range to an Excel table, which will put a filter on the columns' headings. Or just select all the data and add filter (in the Ribbon-Data Tab - select the filter button.

5. Sort the data in both columns by the first column.

You will get all numbers in the second column ordered randomly. As they are explicit numbers their order does not change unless you explicitly re-sort the table. You can copy/paste numbers from the second column elsewhere in your Workbook or use them in situ.

The first column will change every time the sheet is recalculated, which will be triggered among other things by sorting, so every time you sort the table you will get a new random order of the numbers in the second column.

Note that by using the simple RAND function (instead of RANDBETWEEN) you will get a series of 15-decimal-digit random numbers in the first column - not much chance for repetition, but as with the original solution it wouldn't matter.

2019-01-20 14:13:32

Willy Vanhaelen

Sub FillRand()

Dim X As Long, RandIndex As Long, Nums As Variant, Cell As Range

Randomize

Nums = Evaluate("ROW(1:" & Selection.Count & ")")

X = UBound(Nums)

For Each Cell In Selection

RandIndex = Int(X * Rnd + 1)

Cell.Value = Nums(RandIndex, 1)

Nums(RandIndex, 1) = Nums(X, 1)

X = X - 1

Next Cell

End Sub

I did a test in Excel 2007 for a whole column and it took only 16 seconds to process the more than a million cells.

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