Adding and Subtracting Integers
Date: 5/29/96 at 16:42:52 From: Jason Johnson Subject: Adding and subtracting integers Hello Dr.Math... I am currently in grade 8 and I am doing adding and subtracting integers. I really can't grasp this concept. Could you please help me? Your ever-faithful friend, Jason Johnson
Date: 6/25/96 at 15:29:39 From: Doctor Robert Subject: Re: Adding and subtracting integers Dear Jason, Probably the easiest way to 'visualize' addition and subtraction of integers is to use a number line. I am sure that you are familiar with a number line. If you need to add two integers you go to the point on the number line which represents the first number and then you count to the right the number of dots equal to the second number. It doesn't matter which number of your sum you call the first number and which you call the second number. For example, suppose that you have to add 12 + 5. Go to 12 on the number line and then count 5 dots to the right. What number did you land on? 17! And 17 is the sum of 12 and 5. You could have gone to 5 and then counted 12 dots to the right. You would still land on the number 17. For subtraction, you must go to the first number and then move LEFT the number of dots corresponding to the second number. For example, 17 - 9. Go to 17 and then move LEFT 9 dots. You wind up on 8 which is the correct answer. I hope that this helps. It gets a little bit more complicated when you have signed numbers to add and subtract. -Doctor Robert, The Math Forum Check out our web site! http://mathforum.org/dr.math/
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