GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 31 May 2020, 00:22 ### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # If a, b are positive integers, is a/b a terminating decimal?

Author Message
TAGS:

### Hide Tags

Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 9006
GMAT 1: 760 Q51 V42
GPA: 3.82
If a, b are positive integers, is a/b a terminating decimal?  [#permalink]

### Show Tags 00:00

Difficulty:   25% (medium)

Question Stats: 69% (00:38) correct 31% (00:55) wrong based on 86 sessions

### HideShow timer Statistics

If a, b are positive integers, is a/b a terminating decimal?

1) a is a multiple of 2
2) b is a factor of 10

_________________
Manager  S
Joined: 05 Dec 2016
Posts: 227
Concentration: Strategy, Finance
GMAT 1: 620 Q46 V29 Re: If a, b are positive integers, is a/b a terminating decimal?  [#permalink]

### Show Tags

For a/b to be a terminating decimal, b should have either 2 or 5 or both as its prime factors
(2) If b is a factor of 10, and 10 has 2 and 5 as its prime factors, then b can be 2;5;10 which means that a/b is a terminating decimal
Sufficient

Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 9006
GMAT 1: 760 Q51 V42
GPA: 3.82
If a, b are positive integers, is a/b a terminating decimal?  [#permalink]

### Show Tags

Forget conventional ways of solving math questions. In DS, VA (Variable Approach) method is the easiest and quickest way to find the answer without actually solving the problem. Remember that equal number of variables and independent equations ensures a solution.

The first step of VA(Variable Approach) method is modifying the original condition and the question, and rechecking the number of variables and the number of equations.

The property that an irreducible fraction a/b is a terminating decimal depends on the denumerator only. When the denumerator of an irreducible only has 2 and 5 as prime factors, it is a terminating decimal.
Thus, only condition 2) is sufficient.
Therefore, B is the answer unlike our expectation.

Normally for cases where we need 2 more equations, such as original conditions with 2 variables, or 3 variables and 1 equation, or 4 variables and 2 equations, we have 1 equation each in both con 1) and con 2). Therefore, C has a high chance of being the answer, which is why we attempt to solve the question using 1) and 2) together. Here, there is 70% chance that C is the answer, while E has 25% chance. These two are the key questions. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer according to DS definition, we solve the question assuming C would be our answer hence using con 1) and con 2) together. (It saves us time). Obviously, there may be cases where the answer is A, B, D or E.

_________________
Intern  B
Joined: 19 Jan 2018
Posts: 1
Re: If a, b are positive integers, is a/b a terminating decimal?  [#permalink]

### Show Tags

MathRevolution - It is not mentioned that a and b are distinct Integers. therefore, it is possible that a=b, in that case, a/b is not a decimal, it is an Integer. Hence the answer should be E Re: If a, b are positive integers, is a/b a terminating decimal?   [#permalink] 05 Aug 2019, 08:59

# If a, b are positive integers, is a/b a terminating decimal?  