That happened to me before. I was doing a hard equation and put in 7*5. Then I needed to get something from my locker and I forgot to clear my calculator. Someone saw my calculator and thought I was really stupid
Sometimes(actually most of the times) when I'm doing a maths test, i'd get really worried and i'll forget everything and i'd have to check if 2+2 is 4 on the calculator.
Woooh, 5x4 ( that's me trying to be a ghost I'm not a spastic)