Links of good random number generators
http://www.randomnumberegenerator.com/
How to generate a random number in TI-83 (or any similar model)
Press MATH and choose the PRB tab. Then choose #5: randInt(). Parameters: randInt(min, max).
For example:
randInt(1, 100) will generate a random number between 1 – 100, used to determine hit or crit attack.
randInt(3, 12) will generate a random number between 3 – 12, used to determine the amount of damage.