What reason justifies right are angles?

How does the position ofa digit in a number relate to its value? What is 7 percent of 560? What is 36.75 percent as a fraction in simplest form? Are there any whole numbers that are not prime or composite? How do you solve y-3x 15? What is prime factorization 1274? How do you solve 3n equals 36? What is the meaning of addition with carrying? What is 2 over 16 in its lowest terms? How can you tell if the sum is going to be Positive or negative? What is associate property of multiplication? A rectangle has an area of 18 square millimeters how many square megameters would this be? What is the size of a obtuse angle? How do you time 18 minutes with a ten minute sand timer and a ten minute one? What is a 4 degrees angle called? What is the root for unstoppable? What is the diameter of a circle if the circumference is 25 inches? What is the order of magnitude for the number of issues of the New York times published each year? How many gallons in 15 by 33 by 4 foot pool? What number is halfway between 2.6 and 5.8?