text: if you started with 5 and added 10 + 15 + 20 + 25 + 30... all the way to 995, adding 5 more each time, what wo ...what would you get? sum = 5 + 10 + 15 + 20 + 25 + ... + 995 sum = 5*(1 + 2 + 3 + 4 + 5 + ... + 199) sum = 5*(199*200/2) sum = 99500 ------------------------------------------ remember that... s = 1 + 2 + 3 + 4 + ... + n = n(n+1)/2