Answer: in order to calculate the average, add the numbers and divide by how many numbers there are. For example, if I want to know my test score average in a class and my test scores are 85, 90, and 70. First add 85+90+70 = 245. After that, divide by 3 because there are three test scores. 245/3 = 81.66. The average test score is 81.66%