What is the tens digit of positive integer x ? : GMAT Data Sufficiency (DS)
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What is the tens digit of positive integer x ?

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What is the tens digit of positive integer x ? [#permalink]

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19 Mar 2012, 09:59
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What is the tens digit of positive integer x ?

(1) x divided by 100 has a remainder of 30.
(2) x divided by 110 has a remainder of 30.
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Re: What is the tens digit of positive integer x ? [#permalink]

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19 Mar 2012, 10:10
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What is the tens digit of positive integer x ?

(1) x divided by 100 has a remainder of 30 --> x=100q+30: 30, 130, 230, ... as you can see every such number has 3 as the tens digit. Sufficient.

(2) x divided by 110 has a remainder of 30 --> x=110p+30: 30, 140, 250, 360, ... so, there are more than 1 value of the tens digit possible. Not sufficient.

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Re: What is the tens digit of positive integer x ? [#permalink]

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19 Jun 2014, 08:48
Bunuel wrote:
What is the tens digit of positive integer x ?

(1) x divided by 100 has a remainder of 30 --> x=100q+30: 30, 130, 230, ... as you can see every such number has 3 as the tens digit. Sufficient.

(2) x divided by 110 has a remainder of 30 --> x=110p+30: 30, 140, 250, 360, ... so, there are more than 1 value of the tens digit possible. Not sufficient.

Question 1) x divided by 100 has a remainder of 30 --> x=100q+30: 30, 130, 230, ... as you can see every such number has 3 as the tens digit. Sufficient. QUESTION :How exactly are 30, 130, 230 computed?
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Re: What is the tens digit of positive integer x ? [#permalink]

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19 Jun 2014, 08:53
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sagnik242 wrote:
Bunuel wrote:
What is the tens digit of positive integer x ?

(1) x divided by 100 has a remainder of 30 --> x=100q+30: 30, 130, 230, ... as you can see every such number has 3 as the tens digit. Sufficient.

(2) x divided by 110 has a remainder of 30 --> x=110p+30: 30, 140, 250, 360, ... so, there are more than 1 value of the tens digit possible. Not sufficient.

Question 1) x divided by 100 has a remainder of 30 --> x=100q+30: 30, 130, 230, ... as you can see every such number has 3 as the tens digit. Sufficient. QUESTION :How exactly are 30, 130, 230 computed?

If q=0, then x=30;
If q=1, then x=130;
If q=2, then x=230;
If q=3, then x=330;
...

All these numbers when divided by 100 gives the remainder of 30.

Generally, 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 $$15 = 6*2 + 3$$.

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

This formula can also be written as $$\frac{y}{x} = q + \frac{r}{x}$$.

You really need to brush up fundamentals:
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

Hope this helps.
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Re: What is the tens digit of positive integer x ? [#permalink]

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19 Aug 2015, 06:06
This is interesting am benefiting well
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Re: What is the tens digit of positive integer x ? [#permalink]

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17 Nov 2016, 18:22
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Re: What is the tens digit of positive integer x ?   [#permalink] 17 Nov 2016, 18:22
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