The calculator is useful to us to help calculate the results fast, comfortable, where users do not have to think, and the results were valid. If you are working, it is faster. And the calculator will also take to the Mall as well. But in using the calculator, so we should use as much as needed. If this is an easy calculation calculator should not be used. And users don't have to train the brain to calculate. As a result, the performance of the user's computing idea reduced to.