Easy Excel Random Number Generator

Earlier this month, I got a request from our city manager asking if I could randomly select 150 people from a mailing list. No darts allowed. I think the purpose was to do a survey, but maybe it was to select contest winners. I didn’t ask. The good news is Microsoft Excel has a random number generator. Excel actually has two similar randomizer functions in the Math & Trig category. But there are differences between the two.

While I’m sure other software programs have a randomizer function, I chose Excel because that was the source file format. If you want to get technical, I’m really dealing with pseudorandom numbers. For my purposes, I wasn’t worried about the differences.

Excel’s RAND and RANDBETWEEN Function

Excel’s RAND function is a pretty simple function on the surface. As you can see below, simply typing =RAND() in a cell produces tiny random numbers.

  • 0.19934724
  • 0.796184684
  • 0.717061354
  • 0.32105009
  • 0.221891585

Personally, I prefer whole numbers, which are why I opted to use another Excel Math & Trig function called RANDBETWEEN. You may need to install the Analysis Toolpak add-in.

One advantage of RANDBETWEEN is you specify a low and high-end range. For example, =RANDBETWEEN(1,5000) would generate random whole numbers between 1 and 5000. This is important as you don’t want to duplicate entries. It’s best if you choose a top value much higher than what you need.

With either Excel function, I can add a column to my spreadsheet and create a random value for each row alongside the person’s name. That column can then be used to sort the list.

How to Create Random Numbers

In the instructions below, I’ve started with a chronological list of US presidents and wish to randomly select 5 based on the smallest value of a random number I’ll create.

  1. Open your Excel spreadsheet.
  2. Add a column for Order in Column A.
  3. Add a column for Random in Column C.
  4. From the Formulas menu, select Calculation Options.
Excel Formula menu with Calculation Options highlighted.
Setting Excel Calculation Options.
  1. Select Manual calculations.
  2. In cell C1, type =RANDBETWEEN(1,5000). Alternatively, you may use the Insert Function button and fill out the dialog as below.
Excel function dialog for RANDBETWEEN
Adding in RANDBETWEEN arguments
  1. Double-click the lower-right corner of C2. This will copy the formula down the column.
Copying the RANDBETWEEN formula down the column.
Double-click the lower right corner to copy the formula
  1. In cell A1, type 1.
  2. In cell A2, type 2. This is to establish the sequential number pattern.
  3. Double-click the lower-right corner of cell A2. This should fill in the original order range for your column.
Filling in original sort order.
Adding in the original sort order
  1. Click the Select All button. It’s the green triangle above the numbered rows.
  2. From the Data menu, select Sort. I opted to go from Smallest to Largest.
Sort dialog with Random column and Smallest to Largest.
Sorting list by Random number value
  1. Click OK.
  2. From here, I can select how many rows are needed, such as 5.

Cautionary Notes

The main point to remember about using either randomizer function is to turn off Excel’s automatic recalculation. Otherwise, it’s too easy to have the random values update. If that poses a problem, you can copy the Random column to a new column and use Paste Special and Values. You’ll no longer have the underlying formula.

RANDBETWEEN poses another issue if you use small values. For example, I first used =RANDBETWEEN(1,50), figuring the range was larger than the number of presidents. I soon discovered it produced duplicate number values.

Although my original task was to select 150 names from an Excel spreadsheet, you can use these randomizer functions elsewhere. You could create a spreadsheet with many nice things to do for others and create your “Random Act of Kindness” list.

Excel 2019 All-in-One For Dummies
Harvey, Greg (Author); English (Publication Language); 816 Pages - 10/26/2018 (Publication Date) - For Dummies (Publisher)

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