• Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer

OG2016 - If n is a prime number greater than 3

This topic has 1 expert reply and 1 member reply
boomgoesthegmat Senior | Next Rank: 100 Posts Default Avatar
Joined
25 Apr 2016
Posted:
93 messages
Thanked:
1 times

OG2016 - If n is a prime number greater than 3

Post Sun May 01, 2016 9:37 am
Elapsed Time: 00:00
  • Lap #[LAPCOUNT] ([LAPTIME])
    If n is a prime number greater than 3, what is the remainder when n^2 is divided by 12?

    A) 0
    B) 1
    C) 2
    D) 3
    E) 5

    OA: B

    Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
    Post Sun May 01, 2016 9:48 am
    boomgoesthegmat wrote:
    If n is a prime number greater than 3, what is the remainder when n^2 is divided by 12?

    A) 0
    B) 1
    C) 2
    D) 3
    E) 5

    OA: B
    A nice fast approach is to TEST a possible value of n. Since n must be a prime number that’s greater than 3, let’s TEST n = 5

    If n = 5, then n² = 5² = 25, and when we divide 25 by 12, we get 2 with REMAINDER 1

    Answer: B

    Cheers,
    Brent

    _________________
    Brent Hanneson – Founder of GMATPrepNow.com
    Use our video course along with Beat The GMAT's free 60-Day Study Guide

    Check out the online reviews of our course

    GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
    OptimusPrep Master | Next Rank: 500 Posts
    Joined
    13 Mar 2015
    Posted:
    410 messages
    Followed by:
    7 members
    Thanked:
    120 times
    GMAT Score:
    770
    Post Mon May 02, 2016 7:32 pm
    boomgoesthegmat wrote:
    If n is a prime number greater than 3, what is the remainder when n^2 is divided by 12?

    A) 0
    B) 1
    C) 2
    D) 3
    E) 5

    OA: B
    We can solve this problem by testing values easily.
    Assume n = 7, n^2 = 49
    Remainder of (49/12) = 1

    Another approach: Always remember that any prime number apart from 2 is of the form (6k +- 1)

    Assume n = 6k + 1, n^2 = 36k^2 + 12k + 1
    Remainder of (n^2/12) = 1

    Assume n = 6k - 1, n^2 = 36k^2 - 12k + 1
    Remainder of (n^2/12) = 1

    Correct option: B

    _________________
    Ankur
    99th Percentile GMAT Tutor | Optimus Prep™

    Optimus Prep™ GMAT Courses:
    www.Optimus-Prep.com/GMAT

    Free Online Trial Hour:
    http://www.optimus-prep.com/request-free-online-trial-hour/

    Free GMAT Study Plan:
    http://www.optimus-prep.com/ebook/

    Optimus Prep™ Rates:
    GMAT Private Tutoring Online: $80-100/hr.*
    GMAT Private Tutoring In-Person: $130-150/hr.*
    GMAT On Demand Course: $299 (Use Discount Code BEATTHEGMAT111)*

    *All GMAT Courses Have A 50 Points Score Improvement Or Full Refund Guarantee

    Best Conversation Starters

    1 Vincen 180 topics
    2 lheiannie07 61 topics
    3 Roland2rule 54 topics
    4 ardz24 44 topics
    5 VJesus12 14 topics
    See More Top Beat The GMAT Members...

    Most Active Experts

    1 image description Brent@GMATPrepNow

    GMAT Prep Now Teacher

    155 posts
    2 image description Rich.C@EMPOWERgma...

    EMPOWERgmat

    105 posts
    3 image description GMATGuruNY

    The Princeton Review Teacher

    101 posts
    4 image description Jay@ManhattanReview

    Manhattan Review

    82 posts
    5 image description Matt@VeritasPrep

    Veritas Prep

    80 posts
    See More Top Beat The GMAT Experts