The point is that you must use your hands and feet first in solving any problem in mathematics....The way to use your feet is to plant them solidly in the middle of the problem and take a good look around. You can form a rough general idea of the answer....Then you use your hands. Take a firm grasp of what you have to work with. Know what it is that you are going to multiply or divide or add or subtract to get what you want. Then...and only then, go to work with your head.
Romping Through Mathematics, 1947