Adding Positive and Negative NumbersDate: 05/15/2002 at 17:02:52 From: Kiara Subject: adding integers The problem says state if the sum 9 + (-12) is positive, negative,or zero. So if I wanted to add the numbers, how should I begin adding it? Date: 05/15/2002 at 17:30:54 From: Doctor Ian Subject: Re: adding integers Hi Kiara, Let's look at a smaller version of the same problem: 3 + (-5) = (1 + 1 + 1) + (-1 + -1 + -1 + -1 + -1) = (1 + -1) + (1 + -1) + (1 + -1) + -1 + -1 = 0 + 0 + 0 + -1 + -1 = -2 Note that I could have done it more simply this way: 3 + (-5) = 3 + (-3 + -2) = (3 + -3) + -2 = 0 + -2 = -2 Sometimes you 'use up' the negative number instead of the positive one: 5 + -3 = (2 + 3) + -3 = 2 + (3 + -3) = 2 + 0 = 2 Does this help? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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