Dividing 800 by 500
From: Anonymous Date: Mon, 7 Nov 1994 10:38:30 -0500 Subject: Re: Ask Dr. Math: on-line math problem solvers Dear Doctor Math, My name is Damon T Stallings and I am 9 years old. I go to the William Monroe Trotter School,in Roxbury, Mass. I have a math problem for you. How can I divide 800 by 500? Your friend, Damon
From: Dr. Sydney Date: Mon, 7 Nov 1994 11:14:24 -0500 (EST) Subject: Re: Ask Dr. Math: on-line math problem solvers Dear Damon, Thanks for writing to Dr. Math! Your question about dividing 800 by 500 is a good question. I'm not sure how you usually think of division, but I usually think of it in 2 ways: 1) as a fraction: So the problem of dividing 800 by 500 is equivalent to reducing the fraction : 800 --- 500 into simpler terms. One way to do this is to factor the number in the numerator (top) of the fraction and the number in the denominator (bottom) of the fraction, and then cancel common factors. When I say factor the number, I mean write the number as the product of smaller numbers. Keep in mind when we factor 800 and 500 we are looking for common factors. So, let's try... 800=8x100 and 500=5x100, right? So we can rewrite our fraction as: 800 8x100 8 100 ---= -----=-- x--- 500 5x100 5 100 But 100 --- = 1, right? 100 So, 800 8 8 ---= - x 1 = - 500 5 5 We can leave our answer like this or we can write it as 1 and 3/5 (do you know why 8/5 = 1 and 3/5?) 2) The other way to do this is using long divison: The problem becomes: _________ 500|800 = ? Well, the way I usually do problems like this is to move the decimal point over the same number of spaces in both 800 and 500. If we move the decimal point over 2 spaces in each (so 500. becomes 5. and 800 becomes 8.) our problem becomes: ____ 5|8 (Note this step is the counterpart to factoring out a 100 the way we did in the first part). So, now we proceed as usual with long division. 5 goes into 8 one time with 3 left over so we have: _1__ 5|8 -5 --- 3. So our answer is 1 with a remainder of 3 or 1 and 3/5. Both of these methods for division are good, so go with whichever makes more sense to you. If you have any questions about what I said, or if you have any other math questions, feel free to write back. --Sydney
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