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Rounding Numbers. Rounding Numbers. Rounding means reducing the digits in a number while trying to keep its value similar . The result is less accurate, but easier to use . Common Method: Decide which the last digit to keep
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Rounding Numbers Rounding means reducing the digits in a number while trying to keep its value similar. The result is less accurate, but easier to use. Common Method: • Decide which the last digit to keep • Leave it the same if the next digit is les than 5 (this is called rounding down) • Increase it by 1 if the next digit is 5 or more (this is called rounding up) • Every place number less than the last digit is replaced with zeros Examples: • Round 174 to the nearest 10. • Round 1.2635 to the tenths place. Keep it the same Less than 5 174 170 Last Digit to Keep Increase it by 1 5 or More 1.2635 1.3 Last Digit to Keep
AP Calculus Rule for Rounding Always round to three decimal places. START FOLLOWING THIS RULE NOW! Example: 5 or more Increase it by 1 1.2635 1.264 Last Digit to Keep
Contextual Rounding Be aware that there are instances where the type of rounding is determined by the context: Example: A can of paint covers 100 square feet. If Ryan needs to paint 925 square feet, how many cans of paint should he purchase? Example: Elizabeth can write 53 words in one minute. How many complete words can she write in 30 seconds? Round up. You must round to a whole number, but using our method of rounding to 9 cans would be too few to paint the entire room. 10 cans Round Down. You must round to a whole number, but using our method of rounding to 27 words is not true (she can not write that many). 26 words