excel functions

MS Excel: RND Function (VBA)

This Excel tutorial explains how to use the Excel RND function with syntax and examples.

Description

The Microsoft Excel RND function allows you to generate a random number (integer value). You can specify the random number to be a value between 2 user-specified numbers.

Syntax

The syntax for the Microsoft Excel RND function is:

Int ((upperbound - lowerbound + 1) * Rnd + lowerbound)

Parameters or Arguments

upperbound
The highest value that the random number can be.
lowerbound
The lowest value that the random number can be.

Applies To

The RND function can be used in the following versions of Microsoft Excel:

  • Excel 2013, Excel 2011 for Mac, Excel 2010, Excel 2007, Excel 2003, Excel XP, Excel 2000

Type of Excel Function

The RND function can be used in Microsoft Excel as the following type of function:

  • VBA function (VBA)

Example (as VBA Function)

The RND function can only be used in VBA code in Microsoft Excel.

Let's look at some Excel RND function examples and explore how to use the RND function in Excel VBA code:

Int ((6 - 1 + 1) * Rnd + 1)
Result: random number between 1 and 6

Int ((200 - 150 + 1) * Rnd + 150)
Result: random number between 150 and 200

Int ((999 - 100 + 1) * Rnd + 100)
Result: random number between 100 and 999

For example:

Dim LRandomNumber As Integer

LRandomNumber = Int ((300 - 200 + 1) * Rnd + 200)

In this example, the variable called LRandomNumber would now contain a random number between 200 and 300.

Add the Randomize function

If you find that you are not getting a truly random number when calling the RND function, you can use the RANDOMIZE function to change the seed value for the RND function's random number generator. The call to the RANDOMIZE function should preceed the call to the RND function.

For example,

'Example provided by techonthenet.com

Sub Macro1

   Dim LRandomNumber As Integer

   Randomize
   LRandomNumber = Int ((300 - 200 + 1) * Rnd + 200)

End Sub

In this example, the variable called LRandomNumber would now contain a random number between 200 and 300. The Randomize function would ensure that the number generated is truly random by initializing the random number generator with a seed value that is equivalent to the system timer.

Warning: If you don't call the Randomize function before calling the Rnd function, the Rnd function may return the same random number value each time. And therefore, you may not get a truly random number.

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