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The value of two digit integer

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The value of two digit integer

by yass20015 » Mon Aug 10, 2015 11:45 am
What is the value of the two-digit positive integer n?
1- The sum of the digits in n is 12
2- If the digits in a are reversed, the value of the number formed is 36 more than the value of n.

The answer is C)Together. But why not B ? Why the statement 2- alone is not enough ? Can we found other numbers than 84 and 48 ?

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Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Mon Aug 10, 2015 12:01 pm
yass20015 wrote:What is the value of the two-digit positive integer n?
1- The sum of the digits in n is 12
2- If the digits in a are reversed, the value of the number formed is 36 more than the value of n.

The answer is C)Together. But why not B ? Why the statement 2- alone is not enough ? Can we found other numbers than 84 and 48 ?

Thanks
How about 37 and 73?
Or 26 and 62?

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by Max@Math Revolution » Thu Aug 20, 2015 10:08 am
In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem.
Remember equal number of variables and equations ensures a solution.


=> Since we have 2 variables (units digit and tens digit) in the original condition, we need 2 equations to solve the problem and thus the answer is C. (1) 1 equation, (2) 1 equation

=> 2) is not the answer because the number of n is NOT unique, NOT sufficient,





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