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Remainders: Tips and hints

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Joined: 02 Sep 2009
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23 Jun 2014, 03:33
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Remainders: Tips and hints

 ! This post is a part of the Quant Tips and Hints by Topic Directory focusing on Quant topics and providing examples of how to approach them. Most of the questions are above average difficulty.

DEFINITION
If $$x$$ and $$y$$ are positive integers, there exist unique integers $$q$$ and $$r$$, called the quotient and remainder, respectively, such that $$y =divisor*quotient+remainder= xq + r$$ and $$0\leq{r}<x$$.

For example, when 15 is divided by 6, the quotient is 2 and the remainder is 3 since $$15 = 6*2 + 3$$.

TIPS
1. $$0\leq{r}<x$$ means that remainder is a non-negative integer and always less than divisor.

2. When $$y$$ is divided by $$x$$ the remainder is 0 if $$y$$ is a multiple of $$x$$.
For example, 12 divided by 3 yields the remainder of 0 since 12 is a multiple of 3 and $$12=3*4+0$$.

3. When a smaller integer is divided by a larger integer, the quotient is 0 and the remainder is the smaller integer.
For example, 7 divided by 11 has the quotient 0 and the remainder 7 since $$7=11*0+7$$

4. The possible remainders when positive integer $$y$$ is divided by positive integer $$x$$ can range from 0 to $$x-1$$.
For example, possible remainders when positive integer $$y$$ is divided by 5 can range from 0 (when y is a multiple of 5) to 4 (when y is one less than a multiple of 5)..

5. If a number is divided by 10, its remainder is the last digit of that number. If it is divided by 100 then the remainder is the last two digits and so on.
For example, 123 divided by 10 has the remainder 3 and 123 divided by 100 has the remainder of 23.

This week's PS question
This week's DS Question

Theory on remainders problems: remainders-144665.html

Units digits, exponents, remainders problems: new-units-digits-exponents-remainders-problems-168569.html

All DS remainders problems to practice: search.php?search_id=tag&tag_id=198
All PS remainders problems to practice: search.php?search_id=tag&tag_id=199

Please share your Remainders tips below and get kudos point. Thank you.
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Re: Remainders: Tips and hints [#permalink]

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31 Jan 2018, 14:07
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Remainders: Tips and hints   [#permalink] 31 Jan 2018, 14:07
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