Rounding MillionsDate: 08/24/97 at 16:15:03 From: Jerry Tuttle Subject: Question on Rounding Dear Dr. Math, I guess I have never understood the rules about rounding of numbers. Of course 5 or greater rounds up and 4 or less rounds down, but how many significant digits does this affect? I amlooking at the number 308,499,000 and I want to round it to the nearest million; is it 308 million ignoring the 99, or is it 309 million? Thank you. Date: 08/25/97 at 09:22:30 From: Doctor Jerry Subject: Re: Question on Rounding Hi Jerry, One way of thinking about rounding is to imagine a number line. Since you want to round to the nearest million, imagine a number line: ----------|----------|----------|----------|----------| 306 307 308 309 The vertical segments mark the numbers 306 million, 307 million, 308 million, and 309 million. Now imagine plotting the number 308,499,000. I'll try to indicate its position below, with a *. ----------|----------|----------|----------|----------| 306 307 308 * 309 It's a little bit closer to 308 than 309 (308,500,000 would be at the middle point). Hence, if you round to the nearest million, you'll get 308,000,000. -Doctor Jerry, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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