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GMAT's rounding algorithm

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GMAT's rounding algorithm

by vishal.pathak » Sun Apr 01, 2012 8:27 am
Hi All,

What rounding algorithm is used in GMAT

What is the result when x is rounded to the nearest hundredth?
(1) When x is rounded to the nearest thousandth the result is 0.455
(2) The thousandths digit of x is 5
I thought 5 or greater is rounded up and the 0-4 are rounded down. So IMO A, OA is C
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by Bill@VeritasPrep » Sun Apr 01, 2012 8:55 am
For Statement 1, if x is .4546, then it will round to .455. If we round to the nearest hundredth, then it is .45. If x is .4551, it rounds to .455 as well. If we round to the nearest hundredth, however, it would be .46. Since we can get two different values, S1 is insufficient.

S2 is more or less meaningless on its own, but when combined with S1 we know that the result will be .46; a thousandths digit of 5 means we round the hundredths digit up.
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by vishal.pathak » Sun Apr 01, 2012 9:26 am
Bill@VeritasPrep wrote:For Statement 1, if x is .4546, then it will round to .455. If we round to the nearest hundredth, then it is .45. If x is .4551, it rounds to .455 as well. If we round to the nearest hundredth, however, it would be .46. Since we can get two different values, S1 is insufficient.

S2 is more or less meaningless on its own, but when combined with S1 we know that the result will be .46; a thousandths digit of 5 means we round the hundredths digit up.
Hi Bill,

So does this mean that we have to consider the tenthousandths digit as well while rounding to the tenths digit.

Please state the process of rounding that should be followed in GMAT

Thanks for your help

Regards,
Vishal
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by Bill@VeritasPrep » Sun Apr 01, 2012 10:37 am
To round to a given digit, we look at the digit to the right of it. If it is 1-4, we round down. If it is 5-9, we round up.

In Statement 1, we are given .455 as a value for x, but that is already a rounded value. We don't know what the actual thousandths digit is (it could be 4 or 5 as my examples illustrated), so we don't know how to round the hundredths digit.
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by seal4913 » Sun Apr 01, 2012 1:45 pm
I know it is just semantics but if it is 1-4 it is kept the same... the last digit just drops off
Bill@VeritasPrep wrote:To round to a given digit, we look at the digit to the right of it. If it is 1-4, we round down. If it is 5-9, we round up.

In Statement 1, we are given .455 as a value for x, but that is already a rounded value. We don't know what the actual thousandths digit is (it could be 4 or 5 as my examples illustrated), so we don't know how to round the hundredths digit.
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