Answer:
If you are talking math this is what you do: line your group of numbers into a line from least to greatest. Take your least number and your greatest number and basically subtract to see how much is in between. Example:
4 7 9 3 8 (take your numbers and line them from least to greatest) = 3 4 7 8 9
Now take your least number which in this case would be the 3 and your greatest which in this case would be 9. 9-3=6. There you go, 6 is the amount between 9 and 3. That's your range.