What is 21-20?

What is the mathematical standard form for 0.00417? What is 2.5 as a fraction in it simplest form? Who invented cross multiplication? What is 56 added to 33? When i came first in my class? What is the median of 2 3 3 5 5 6? How do you write this number three hundred twenty three thousand? What is 36 over 63 simplified? What is 9 out of 12 in simplest form? Is negative one half an irrational number? What does subtracting mean? How many 10 centimeter lengths can be cut from a 4 meter long roll? Is the equation of a line that is perpendicular to a line that goes through points at ( and ndash1 5) and (1 and ndash3) and contains point (4 -4)? How many florins are in a pound? What are the characteristics of the leader in 8000 BC? Can you simplify 6 over 9? What is 15 a prime number or composite? What is a Royalty in Math? What percent of 260 is 390? What is the largest odd number that you can form with the digits 38 and 6?