In many GRE questions, you may be asked to in the course of solving a problem to present your answer to nearest such- and – such. So for such questions, you need to acquire the skills of rounding up.
1. Math Basics for GRE Exam preparation – Part I
Rounding techniques
In many GRE questions, you may be asked to in the course of solving a problem to present
your answer to nearest such- and – such. So for such questions, you need to acquire the
skills of rounding up.
But what is rounding
Rounding means reducing the digits in a numer while trying to keep its value similar. The
result is less accurate, but easier to use.
Here are some problem areas, where things get a bit perplexing.
Rounding to the nearest integer
You may need to convert a decimal to the nearest integer.
Trick
14.3 -> 14
15.9 -> 16
Did you observe the logic?
If the digit immediately after the decimal is {0,1,2,3,4}, then we round it down, which means
the units digit remains the same.
If the digit immediately after the decimal is {6,7,8,9}, then we round it up, which means the
units digit increases by 1.
What about 7.5, 8.5, 9.5 or such numbers?
Any number with a 5 in the tenths place is rounded up, which means the units digit increases
by 1.
Rounding up negative values
+5.5 -> 6
+5.3 -> 5
-5.5 -> -6
-5.3 -> -5
2. Quite contrary to positive numbers, negative values are rounded down if the digits in the
tenths place are {5,6,7,8,9) and they are rounded up if the digits in the tenths place are
{0,1,2,3,4}
Note: Avoid rounding up twice
Generally we have a tendency to round up things twice, but bear in mind that rounding is a
single step process.
For eg:
14.49
Now for the above number, if your thought process is somewhat like this, ........
“I see 9 at the extreme end, so 4 will become 5 and since 5 is obtained in the tenths place, the
number becomes 15 when rounded up.”
...........then watch out. You are treading the wrong path.
The correct thought process should be
“I see 4 and nothing else, immediately after the decimal. So the number when rounded
becomes 14.”
Bingo!!!!!!! You are on the right track.
Some simply confusing roundings, that can pester you on your GRE
12.320 - > 12.30
12.321 - > 12.30
12.322 - > 12.30
12.323 - > 12.30
12.324 - > 12.30
12.325 - > 12.35
12.326 - > 12.35
12.327 - > 12.35
12.328 - > 12.35
3. 12.329 - > 12.35
12.330 - > 12.35
Remember, GRE loves testing fundamentals. Understanding the logic behind the above
mentioned roundings will definitely help you in a question or two.
Let us check out an ETS numeric entry question
A merchant made a profit of $5 on the sale of a sweater that cost the merchant $15. What is
the profit expressed as a percent of the merchant's cost?
Give your answer to the nearest whole percent.
%
Explanation
The percent profit is
percent, which is 33%, to the nearest whole
percent. Thus, the correct answer is 33% (or equivalent).
If you use the calculator and the Transfer Display button, the number that will be
transferred to the answer box is 33.333333, which is incorrect since it is not given to the
nearest whole percent. You will need to adjust the number in the answer box by deleting all
of the digits to the right of the decimal point (using the Backspace key).
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