Answer: add over and over again
Step-by-step explanation:How do you get from 0 to 3? you add 3 to 0. Then, how do you get from 3 to 8? you add another 3 but then you a 2 too, so then 8. Lastly, my last example, how to get from 8 to 15. You take five, and then add 2 to it and add that number(then number you get when you add 5+1), 7 to 8.