Link: https://www.gregmat.com/quizzes/quiz/prepswift-quant-tickbox-quiz-1-arithmetic-column-1 (Question 7)
For this question, I was wondering why I don’t have to add one after subtracting the last value from the first like Greg outlined in finding the interval between integers?
Subtraction finds the distance between two points on a number line, which is exactly what this question is asking for.
For instance, the distance between -7 and - 6 is just 1, right?
When you add 1 to the difference, you are counting the number of integers in that interval. For example, adding 1 to the result above (1 + 1) gives you 2, which is the number of integers in the interval [-7, -6]. Since the question only asks for distance, you stop after subtracting.