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Intern
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Rounding up or rounding down [#permalink]
 20 Sep 2010, 12:55
Hello,
I am not 100% sure whether to round up an integer, say 2.5, to 3.0 or round down to 2.0. And what should happen in case of -2.5?
Does such situation occur on GMAT?
Please respond.
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Manager
Joined: 16 Sep 2010
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Re: Rounding up or rounding down [#permalink]
20 Sep 2010, 13:18
I always adhere to the rule of 5, if its .5 or above you round up. This is obviously inverse for negative numbers.
You may encounter this but its unlikely as most interaction with strictly integers is limited to data sufficiency and you do not need to actually solve these only prove that they can be solved.
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Re: Rounding up or rounding down [#permalink]
20 Sep 2010, 13:32
Rounding is simplifying a number to a certain place value. To round the decimal drop the extra decimal places, and if the first dropped digit is 5 or greater, round up the last digit that you keep. If the first dropped digit is 4 or smaller, round down (keep the same) the last digit that you keep. Example:5.3485 rounded to the nearest tenth = 5.3, since the dropped 4 is less than 5. 5.3485 rounded to the nearest hundredth = 5.35, since the dropped 8 is greater than 5. 5.3485 rounded to the nearest thousandth = 5.349, since the dropped 5 is equal to 5. So 2.5 rounded to the nearest integer equals to 3. As for rounding negative numbers: you won't need this for GMAT, so don't worry about it.
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Re: Rounding up or rounding down [#permalink]
20 Sep 2010, 14:25
Thanks u0422811 and Bunuel.
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Re: Rounding up or rounding down [#permalink]
20 Sep 2010, 14:58
I believe the official rule of gmat is to round up if its .5 or above and down if its .4 or below. Though one must be carefull in some instances where you must round down at all times. For example if the question asks the number of people that can fit into a room, and your calculation gives 11.9, the answer would be 11 rather than 12.
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Re: Rounding up or rounding down [#permalink]
20 Sep 2010, 15:55
The GMAT will occasionally give a crazy rule for rounding, and say any number [x] should always be rounded up/down. They usually rely on "tricking" you on negative numbers. When rounding up/down on a negative number, it may be helpful to visualize the number line to make sure you are rounding in the right direction!
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Re: Rounding up or rounding down
[#permalink]
20 Sep 2010, 15:55
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