rounding numbers. rounding means reducing the digits in a number while trying to keep its value...
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Rounding Numbers
Rounding NumbersRounding 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:
1. Round 174 to the nearest 10.
2. Round 1.2635 to the tenths place.174Last Digit to Keep
Less than 5
170Keep it the same
1.2635Last Digit to Keep
5 or More
1.3Increase it by 1
AP Calculus Rule for Rounding
Always round to three decimal
places.
1.2635Last Digit to Keep
5 or more
1.264Increase it by 1
START FOLLOWING
THIS RULE NOW!
Example:
Contextual RoundingBe 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?
925÷100=9.25 10 cansYou must round to a
whole number, but using our method of rounding to 9 cans would be too few to paint the entire room.
Round up.
53÷2=26.5 26 wordsYou must round to a
whole number, but using our method of rounding to 27 words is not true (she can not write that many).
Round Down.
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