Definition of lumbar puncture. : puncture of the subarachnoid space in the lumbar region of the spinal cord to withdraw cerebrospinal fluid or inject anesthetic drugs.
Rational Numbers A rational number is a number that can be written as a ratio. That means it can be written as a fraction, in which both the numerator (the number on top) and the denominator (the number on the bottom) are whole numbers. The number 8 is a rational number because it can be written as the fraction 8/1.
Pi is an irrational number. 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.