When you need to find the range of a set of numbers, you first must arrange them in order, starting with the lowest and listing them in order to the highest. Take the largest number and subtract the lowest. This answer is the range of that set of numbers. For example, if Sally took 5 tests and her scores were 78, 98, 56, 88 and 90 you would need to arrange them in order (56, 78, 88, 90, 98). Take the largest (98) and subtract the smallest (56). The answer (42) is the range of Sally’s test scores.