document.write( "Question 667115: Simple math question. I know the basics of borrowing when subtracting, but here is when I get stuck. I am subtracting two three digit numbers. 771-252. The 1 becomes an 11, 11-2=9 bring the 7 in the tens column to a 6, 6-5=1. Now I don't bring the 7 in the hundreds column down to a 6. Why is that? In 916-618, the 6 becomes a 16, the 1 is brought down to a zero and becomes a 10, and the 9 is brought down to an 8. Why must all the numbers in 916 be regrouped but not all in 771? \n" ); document.write( "
Algebra.Com's Answer #414915 by math-vortex(648)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "Hi, there--\r\n" );
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document.write( "QUESTION:\r\n" );
document.write( "I am subtracting two three digit numbers. 771-252. The 1 becomes an 11, 11-2=9 bring the \r\n" );
document.write( "7 in the tens column to a 6, 6-5=1. Now I don't bring the 7 in the hundreds column down to \r\n" );
document.write( "a 6. Why is that? In 916-618, the 6 becomes a 16, the 1 is brought down to a zero and \r\n" );
document.write( "becomes a 10, and the 9 is brought down to an 8. Why must all the numbers in 916 be \r\n" );
document.write( "regrouped but not all in 771?\r\n" );
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document.write( "SOLUTION:\r\n" );
document.write( "This is a great question. It shows that you won't accept the mathematics when it doesn't make \r\n" );
document.write( "sense. Excellent! Here is one way to think about this:\r\n" );
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document.write( "Sometimes people will expand the numbers (into ones, tens, and hundreds) so they see what's \r\n" );
document.write( "happening on at a place value level:\r\n" );
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document.write( "771 is equivalent to 700 + 70 + 1\r\n" );
document.write( "252 is equivalent to 200 + 50 + 2\r\n" );
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document.write( "Now let's subtract the ones. We want to subtract 2 from 1. Here we need to regroup (borrow) \r\n" );
document.write( "because we cannot take 2 things from 1 thing without going in the hole. (For example, I can't \r\n" );
document.write( "borrow $2 from you if you only have $1.)\r\n" );
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document.write( "771 = 700 + 60 + 11\r\n" );
document.write( "252 = 200 + 50 +  2\r\n" );
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document.write( "ONES: Subtract 11 - 2 = 9 in the ones column.\r\n" );
document.write( "TENS: Subtract 60 - 50 = 10 in the tens column. We don't need to regroup here because we \r\n" );
document.write( "can take 50 form 60 with out going in the hole. (For example, I can borrow $50 from you if \r\n" );
document.write( "you have $60.)\r\n" );
document.write( "HUNDREDS: Subtract 700 - 200 = 500 in the hundreds column.\r\n" );
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document.write( "Putting this back together, we have 500 + 10 + 9 = 519.\r\n" );
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document.write( "Here's how it looks vertically,\r\n" );
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document.write( "771 = 700 + 70 + 1 = 700 + 60 + 10\r\n" );
document.write( "252 = 200 + 50 + 2\r\n" );
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document.write( "(regroup from tens column to ones column. We take 1 group of ten from the tens column \r\n" );
document.write( "and put in the ones column.)\r\n" );
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document.write( "Subtract:\r\n" );
document.write( "771 = 700 + 60 + 11\r\n" );
document.write( "252 = 200 + 50 + 2\r\n" );
document.write( "-----------------\r\n" );
document.write( "519 = 500 + 10 + 9\r\n" );
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document.write( "In your second example, 916-618, you do have to regroup (borrow) in each column. Let's \r\n" );
document.write( "break the numbers down to show their place value. \r\n" );
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document.write( "916 = 900 + 10 + 6\r\n" );
document.write( "618 = 600 + 10 + 8\r\n" );
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document.write( "ONES: We cannot take 8 things from 6 things without going in the hole, so we need to regroup. \r\n" );
document.write( "When we take 10 from the tens column we have 0 left because 10-10=0.\r\n" );
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document.write( "916 = 900 + 0 + 16\r\n" );
document.write( "618 = 600 + 10 + 8\r\n" );
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document.write( "TENS: We cannot take 10 things from 0 things without going in the hole, so we regroup again \r\n" );
document.write( "from the hundreds column to the tens column.\r\n" );
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document.write( "916 = 800 + 100 + 16\r\n" );
document.write( "618 = 600 + 10 + 8\r\n" );
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document.write( "Now we are ready to subtract.\r\n" );
document.write( "ONES: 16-8 is 8.\r\n" );
document.write( "TENS: 100-10 is 90.\r\n" );
document.write( "HUNDREDS: 800-600 is 200.\r\n" );
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document.write( "Vertically, we have \r\n" );
document.write( "916 = 800 + 100 + 16\r\n" );
document.write( "618 = 600 + 10 + 8\r\n" );
document.write( "--------------------\r\n" );
document.write( "298 = 200 + 90 + 8\r\n" );
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document.write( "I hope this helps. You can email me if you still have questions about this,\r\n" );
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document.write( "Mrs.Figgy\r\n" );
document.write( "math.in.the.vortex@gmail.com\r\n" );
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