How to use the RAND function
What is the RAND function?
The RAND function calculates a random real number greater than or equal to 0 and less than 1. The function is volatile.
What is random?
Each outcome of a random process cannot be predicted with certainty before it occurs. It is unpredictable.
Is the RAND function random?
No, it is pseudo-random. The generated value is not truly random.
What is pseudo-random?
Random numbers created by software like Excel are not truly random, they can be predicted. That is why they are called pseudo-random meaning they look like random values but they are not.
What is volatile?
The function is volatile meaning a new random real number is returned every time the worksheet is calculated.
What is the effect of volatile functions?
They may slow down your worksheet/workbook if you have many volatile functions.
When is the worksheet calculated?
Cells containing non volatile functions are only calculated once or until you force a recalculation, however, volatile functions are recalculated each time you type in a cell and press enter.
Can you stop recalculating a worksheet?
Yes, you can change a setting to manual recalculations.
- Go to tab "Formulas".
- Press with left mouse button on the "Calculation Options" button, a popup menu appears.
- Press with mouse on "Manual".
This stops the automatic recalculations.
How to force a recalculation?
Pressing F9 key will recalculate or refresh all the formulas and values in every worksheet of every workbook you have open.
Pressing Shift+F9 will only recalculate the formulas and values on the single worksheet you're currently viewing or active.
Pressing Ctrl+Alt+F9 is the quickest way to force a full recalculation of absolutely everything in all open workbooks, even if nothing has changed. It ignores whether changes were made or not and completely recomputes.
Are there more volatile functions in Excel?
Yes. OFFSET, TODAY, NOW among others.
| Function | Syntax | Description |
|---|---|---|
| OFFSET | OFFSET(reference, rows, cols) | Returns a cell offset from a reference cell. |
| TODAY | TODAY() | Returns the current date. |
| NOW | NOW() | Returns current date and time. |
| RANDARRAY | RANDARRAY([rows], [columns], [min], [max], [whole_number]) | Returns an array with random numbers. |
| RANDBETWEEN | RANDBETWEEN(bottom, top) | Returns a random whole number between bottom and top |
Note, that conditional formatting is extremely volatile or super-volatile meaning it is recalculated as you scroll through a worksheet.
What other functions return random values?
| Excel Function | Syntax | Description |
|---|---|---|
| RAND() | RAND() | Returns a random decimal number between 0 and 1 |
| RANDBETWEEN | RANDBETWEEN(bottom, top) | Returns a random whole number between bottom and top |
| RANDARRAY | RANDARRAY([rows], [columns], [min], [max], [whole_number]) | Returns an array with random numbers. |
RAND function Syntax
RAND()
RAND function Arguments
The RAND function has no arguments.
RAND function example
Formula in cell B3:
Generate random integers
Generate random values in a given range
'RAND' function examples
The RAND() function In Excel returns a number greater than or equal to 0 (zero) and less than 1. Combining […]
Microsoft Excel has three useful functions for generating random numbers, the RAND, RANDBETWEEN, and the RANDARRAY functions. The RAND function […]
Functions in 'Math and trigonometry' category
The RAND function function is one of many functions in the 'Math and trigonometry' category.
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