Midbrain. The midbrain, also called the mesencephalon, is a small region of the brain that serves as a relay center for visual, auditory, and motor system information. It regulates autonomic functions, those that the body carries out without conscious thought, such as digestion, heart rate, and breathing rate.
A rational number is one that can be expressed as a fraction (or ratio), e.g. 1/3. There are fractions that are near Pi, for example: 22/7 = â¦ 3.142857 (PI = 3.14159265...) A closer fraction is: 355/113 = 3.14159292 However whatever fraction you have, you will never get exactly PI.
But pi is an irrational number, meaning that its decimal form neither ends (like 1/4 = 0.25) nor becomes repetitive (like 1/6 = 0.166666...). (To only 18 decimal places, pi is 3.141592653589793238.) Hence, it is useful to have shorthand for this ratio of circumference to diameter.