Mental math can be like an extention of your natural intuition and vise versa. Ideas that wouldn't otherwise arise can spontaneously come to you because you hav

Mental math can be like an extention of your natural intuition and vise versa. Ideas that wouldn't otherwise arise can spontaneously come to you because you have the feeling in the back of your mind that A<<B, A=B, etc. Sometimes it seems a problem has dozens of possible solutions. Mental math is great for whittling away the less optimal ones quickly. It has been said that the best way to have a good idea is to have alot of ideas. Mental math is the natural companion to testing and refining those ideas in an intuitive but quantitative way.