If you multiply the fraction-0.5 by 10, it becomes -5. Now, you multiply -5 by 9; which is -45. With this number, we can now divide by the original 10 that we used to get -4.5. P.S if the fraction is .45 for example, you would have to multiply it by 100 to get to 45 and then divide it by 100 at the end to get the answer.