Casio was excellent for cheating in math class because it looked like a regular calculator but could work fractions like no other.
So cheating came in when they wanted you to show your work. You could use the casio to quickly find the final answer and then reverse engineer it out in the shown work. So even if they rejected the shown work part you for sure got half credit for having the correct answer. Most times, most professors would see the correct answer and not even check the work.
So you ended up saving a crap load of time for the harder problems that required more writing and thinking and finish it all in the top 5 :D