the bus stop method or chunking both of them are very acurate methods. chunking, eg.if you were doing 21 divided by 3 you would see what time three is 21. with big numbers you can take away small chunks. eg 336dived by 8 10x8=80 see what you are left with then keep on doing it until you get to 0.add up what you have times it by each ti me and you have your anser