Succinctly, pi—which is written as the Greek letter for p, or π—is the ratio of the circumference of any circle to the diameter of that circle. Regardless of the circle's size, this ratio will always equal pi. In decimal form, the value of pi is approximately 3.14
The answer is 90%. You get this answer by multiplying both the numerator and denominator by 5 so 18x5=90 and 20x5=100 giving you a fraction of 90/100 and a percentage of 90%.
