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 →

PS-how many prime numbers are less than 100?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 179
Joined: Tue Jan 08, 2008 7:23 pm
Thanked: 11 times
GMAT Score:590
by nitya34 » Thu Jul 23, 2009 8:38 am
how many prime numbers are less than 100?
options are
22,23,24,25,26
any short cut here?
OA is 25
Last edited by nitya34 on Fri Jul 24, 2009 12:02 am, edited 1 time in total.
Many of the great achievements of the world were accomplished by tired and discouraged men who kept on working.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pmFollowed by: 614 members
Location: Toronto
Thanked: 1710 times
GMAT Score:800

Re: PS-how many prime numbers are less than 100?

by Stuart@KaplanGMAT » Thu Jul 23, 2009 9:18 am
nitya34 wrote:how many prime numbers are less than 100?

any short cut here?
OA is 25
This is not a real GMAT question.

Mathematicians have devoted their entire careers to finding ways to list prime numbers - there is no simple shortcut. The only possible way a GMAT test taker could be expected to answer the question is to actually list all the numbers from 1 to 100 and count the primes.

Where is this question from? What were the answer choices? You should include both of these pieces of info in every post you make on this forum.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 157
Joined: Tue Oct 07, 2008 5:47 am
Thanked: 3 times

by PussInBoots » Fri Jul 24, 2009 10:01 pm
It cannot be GMAT question. The only way to do it is to go through every odd number and check if it's prime or not
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 113
Joined: Thu Jul 16, 2009 11:23 am
Thanked: 15 times
GMAT Score:730

by prindaroy » Fri Jul 24, 2009 11:29 pm
Certainly not a GMAT question. But to answer your question, the number of primes less than can be approximated to n/ln(n-1) = 100/ln(100-1). There have also been several functions to determine number of primes.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1