Rand-multiple

rand-multiple 
    Rand-multiple (Arithmetic operator) 
    Gets a random number. This number can and will change between 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

Use this instead of rand if it will be called more than once in a mission. Unlike rand, this SEXP will re-randomize the number for each call.