Simulating quickly a large number of repetitions of an experiment is a powerful tool in statistics. Simulations can be performed and explored individually by students in the classroom with graphics calculators like the TI83(Plus). Applications are estimating the probability of an event, predicting the profit in a game of chance, approximating the probability distribution of a random variable, drawing samples from a population, testing the quality of the random number generator. These applications will be illustrated with examples.