Problems with Zero; Writing RemaindersDate: 11/07/2001 at 10:16:10 From: lacy Subject: Problem with zero When I do long division I have trouble with some of my answers, where the answer is correct except for one thing in the middle that sometimes contains a zero. For example, when I did this one: 38/1294058 I got the answer 3465 r23/28 but when I checked the answer it read 34065 r23/38 Where am I going wrong? Date: 11/07/2001 at 12:18:43 From: Doctor Peterson Subject: Re: Problem with zero Hi, Lacy. You probably just forgot to write a zero in the quotient when you had to "bring down" an extra digit from the dividend because the remainder was bigger than the divisor. I'll do the problem in a way that avoids that: ____34054_r_6 38 ) 1294058 114 --- 154 152 --- 20 0 <-- the problem is here -- 205 190 --- 158 152 --- 6 (I don't know where one of us copied wrong, but I'll go with this problem anyway!) When I found that 20 was too small to divide by 38, I had to bring down another digit, the 5. When I did that, I was really saying that 20 divided by 38 is 0, so I had to put a zero in the quotient. To make sure I did that, I actually subtracted 0 from 20 as usual, rather than saving space by just putting 5 next to the 20 like this: ____34054_r_6 38 ) 1294058 114 --- 154 152 --- 205 <-- two digits brought down need two digits in 190 quotient --- 158 152 --- 6 You can do it either way, but this helps if you have this problem. Another thing that helps is to make sure you line everything up, so that the digit you get after bringing down the 5 goes over the 5. If something doesn't line up at the end, you know you left something out. Finally, you should always check your answer, which you can do by multiplying 34054 by 38, and then adding the remainder, 6. You should get 1294058. Incidentally, if the book wrote the answer in the form 34065 r23/38 they're not quite right; when you use the remainder to form a fraction, the result is a mixed number and you shouldn't include r ; just write 34065 23/38. You use r when you leave the remainder as a remainder: 34065 r23. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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