Non zero digits

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 113
Joined: Wed Dec 07, 2011 7:20 am
Thanked: 3 times

Non zero digits

by manik11 » Thu Feb 18, 2016 5:41 am
Does the decimal expression of the fraction X/8 have more than 4 non-zero digits?

1. X is a digit
2. X<10

OA :A

I figured 1/8 is 0.125 and rephrased the question to "0.125X more than 4 non-zero digits?"
Multiplied couple of numbers to 0.125 but didn't got more than 3 non zero digits. Chose D.
Experts...Could you please tell me whether my approach was correct? And more importantly where did I go wrong?

User avatar
Legendary Member
Posts: 2663
Joined: Wed Jan 14, 2015 8:25 am
Location: Boston, MA
Thanked: 1153 times
Followed by:128 members
GMAT Score:770

by DavidG@VeritasPrep » Thu Feb 18, 2016 5:50 am
manik11 wrote:Does the decimal expression of the fraction X/8 have more than 4 non-zero digits?

1. X is a digit
2. X<10

OA :A

I figured 1/8 is 0.125 and rephrased the question to "0.125X more than 4 non-zero digits?"
Multiplied couple of numbers to 0.125 but didn't got more than 3 non zero digits. Chose D.
Experts...Could you please tell me whether my approach was correct? And more importantly where did I go wrong?
The rephrase is certainly valid. 1/8 = .125, so clearly x/8 = x*(.125)
Your problem was assuming that x was an integer. Statement 2 only tells us that x is less than 10, so x could be some horrible decimal that would give us more than 4 non-zero digits in x/8.
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course

GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Fri Feb 19, 2016 2:04 pm
Assuming that x is positive, an integer, rational, etc. is one of the testwriters' favorite tricks, so don't sweat it: if you miss this a few times in practice, it makes you that much more annoyed by it and thus more likely to remember it on test day! :)