Rand

rand 
 Rand (Arithmetic operator) 
 Gets a random number. This number will not change on successive calls to this sexp. 
 
 Returns a number. Takes 2 or 3 numeric arguments... 
 1: Low range of random number. 
 2: High range of random number. 
 3: (optional) A seed to use when generating numbers. (Setting this to 0 is the same as having no seed at all)

Comments

If you want to randomize a different number every time a given event is triggered, use rand-multiple.