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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.
Re: n represent the hundredths digit in the number shown above. [#permalink]
02 Dec 2015, 07:15
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n represent the hundredths digit in the number shown above. If the number is rounded to the nearest hundredth, which of the following could be the tenths digit in the rounded number?
Explanation only, will be appreciated.
I got this one in 53 seconds, please let me know in case there is any faster way to solve these kinds of questions.
In theis ques we are given the thousandth digit as 5, so the hundreth digit can take any value from 0-9. For the hundreth digit i considered 2 set of values (i) 0, 1, 2, 3 and (ii) 4, 5, 6, 7, 8, 9. Given that the thousandth digit is 5, the undreth digit has to go up by 1, and correspondingly, the tenth digit should also increase by 1 ( provided the hundreth digit is from the 2nd category. Since B was the only one amongst the feasable ans choise, i selected B .
3.1n5 - if rounded upto tenth digit, it can either be 3.1 or 3.2 . since 1 is not in choice, so 2 is the answer.
30 seconds. strip of the extra information : If the number is rounded to the nearest hundredth
Very good summary!
Rounding can only do two things to a digit that remains in the number: leave a digit unchanged, or increase a digit by 1 (which can reset a 9 to a zero and increase the NEXT digit).
Since the tenths digit is currently a 1, almost everything else in the Q-stem is irrelevant. The tenths digit can never round to anything other than a 1 or a 2, and so (B) is the only possible answer.