Excel: Random Number Generation

• Microsoft Excel 98 Macintosh Edition
• Microsoft Excel for Windows, versions 2.x, 3.x, 4.x, 5.0, 5.0c
• Microsoft Excel for the Macintosh, versions 1.x, 2.x, 3.x, 4.x, 5.0, 5.0a
• Microsoft Excel for Windows NT, version 5.0
• Microsoft Excel for Windows 95, version 7.0

SUMMARY

In Microsoft Excel, the RAND function uses the following iterative method to calculate pseudo-random numbers:

The first random number:

   random_number=fractional part of (9821 * r + 0.211327),
   where r = .5

   random_number=fractional part of (9821 * r + 0.211327),
   where r = the previous random number

MORE INFORMATION

Computers cannot generate truly random numbers. Instead, they return a series of numbers based on a mathematical relationship that simulates "randomness." The "randomness" exhibited by the numbers is a function of the mathematical formula used by the random number generator.

In Microsoft Excel for Windows, adding randomize=1 to the [Microsoft Excel] section of the appropriate .INI file for your version of Microsoft Excel will cause "r" to be determined from the system clock (which adds a further degree of randomness to the numbers generated).

   For this version         The name of your
   of Microsoft Excel       .INI file is this
   -----------------------------------------

   5.0                      EXCEL5.INI
   4.0                      EXCEL4.INI
   3.0                      EXCEL.INI

NOTE: Excel 5.0 defaults to the RANDOMIZE=1 setting. Previous versions of Microsoft Excel defaulted to RANDOMIZE=0.