So the little 5 over the ten (exponent) means that you multiply it by itself 5 times. If it shows a one then its just itself and if its a zero the number really doesn't exist. Its just zero. So that would be 6.4 x 50 divided by 3.2 x 20 because a decimal really just means that you're dividing. Now if the exponent is negative then it just means the exact opposite. You will divide by the number shown. Hope that helps :))