
Question: If m and n are positive integers, is the remainder of \(\frac{10^m+n}{3}\) greater than the remainder of\(\frac{10^n+m}{3}\) ?
“If m and n are positive integers, is the remainder ofgreater than the remainder of?”- is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been taken from the book "GMAT Quantitative Review". GMAT Quant section consists of a total of 31 questions. GMAT Data Sufficiency questions consist of a problem statement followed by two factual statements. GMAT data sufficiency comprises 15 questions which are two-fifths of the total 31 GMAT quant questions.
Answer:
Approach Solution (1):
First of all any positive integer can yield only three remainders upon division by 3: 0, 1, and 2
Since, the sum of the digits \(10^m and 10^n\) of is always 1 then the remainders of \(\frac{10^m+n}{3}\) and are only dependent on the value of the number added to \(10^m and 10^n\). There are three cases:
If the number added to them is: 0, 3, 6, 9, … then the remainder will be 1 (as the sum of the digits of \(10^m and 10^n\) will be 1 more than a multiple of 3);
If the number added tot hem is: 1, 4, 7, 10, …. Then the remainder will be 2 (as the sum of the digits of \(10^m and 10^n\) will be 2 more than a multiple of 3);
If the number added to them is: 2, 5, 8, 11, … then the remainder will be 0 (as the sum of the digits of \(10^m and 10^n\) will be a multiple of 3).
(1) m > n. Not sufficient
(2) The remainder of \(\frac{n}{2}\) is 2. So n could be: 2, 5, 8, 11, ... so we have the third case which means that the remainder of \(\frac{10^m+n}{3}\) is 0. Now, the question asks whether the remainder of \(\frac{10^m+n}{3}\) , which is 0, is greater than the remainder of \(\frac{10^m+n}{3}\) , which is 0, 1, or 2. Obviously it cannot be greater, it can be less than or equal to. So, the answer to the question is NO. Sufficient
Correct option: B
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