Need help with remainder problem

Hi Ana

As you probably know (since you're studying from MGMAT) the algebraic equation that ties the numerator (n), denominator (d), quotient (q) and remainder (r) is n = dq+r. For instance when 13 is divided by 5, the quotient is 2 and the remainder is 3 >> 13 = 5*2 + 3.

When the numerator is smaller than the denominator the integer part of the result of the division is 0. for instance, 5/6 = 0.833. The integer part of the result is another name for the quotient. 5 divided by 6 has a quotient of 0 and a remainder of 5 >> 5 = 6*0 + 5.

In any integer division for which the top is smaller than the bottom, the remainder is the top.

Examples
5/6 has a remainder of 5.
3/12 has a remainder of 3.

To create timed drills with remainder questions, set topic='Number Properties' and difficulty='700+' in the Drill Generator. You can also practice just remainder questions by searching for the keyword 'remainder' in the GMATPrep solutions search page.

Hope that helped,
-Patrick

Here's a simpler way:

x= qy + 5 ........ q is quotient
What should the value of a so that x is minimum??
If q =0 (q cannot be negative, becuase you never get negative quotient)
Hence X = 5
If X =5, that what will be min. the value of Y so that remainder is 5
So Y = 6 (Plugin the values .... if it is difficult to visualize)

Hence XY = 30.

Remainder questions can be a real pain. Most test-takers should either plug in answers or pick numbers. In this particular case, plugging in answer choices (which I didn't see) would probably be a snap. When possible, picking numbers is also quite easy (I believe an example can be found in the OG quant book).

For advanced (85th percentile+) test-takers, knowing certain formulas can be a help, but again, they're a pain to memorize (especially considering everything else you need to know).

Hope this helps...