BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

n is a two digit integer

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 99
Joined: Fri Jul 13, 2012 1:35 amFollowed by: 1 member
Thanked: 1 times
by AJWILL » Sat Aug 04, 2012 12:27 pm
if n is a two digit integer and [(.3)(.009)(.000243)/(.81] *10^n] is an integer. How many values of n are possible ?

[A] 89
90
[C] 91
[D] 92
[E] 93

how to go about it?

OA B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 520
Joined: Sat Apr 28, 2012 9:12 pmFollowed by: 49 members
Thanked: 339 times
GMAT Score:770

by eagleeye » Sat Aug 04, 2012 12:40 pm
AJWILL wrote:if n is a two digit integer and [(.3)(.009)(.000243)/(.81] *10^n] is an integer. How many values of n are possible ?

[A] 89
90
[C] 91
[D] 92
[E] 93

how to go about it?
OA B


I am not sure about the brackets, so I am assuming the expression is:
[(.3)(.009)(.000243)/(.81] * (10^n)

First of all simplify:
[(.3)(.009)(.000243)/(.81] = (3*(10^-1))*(9*10^-3)*(243*10^-5)/(81*10^-2)
= (3*9*243/81)*(10^(-1-3-5+2) = (3*9*3)*10^(-7)= 3^4*10^(-7)

Now the complete expression becomes 3^4*(10^(n-7)). Since 3 and 10 have no factors in common, and this expression is an integer, we need that n-7>=0
=> n >= 7.

Now n is a two digit number. Therefore 10 <= n <=99
Hence range of values of n = 99-10+1 = 89+1 = 90.

B is correct. :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1