Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.

See classes
Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

Newsweek Readers’ Choice Awards 2026 winner: Target Test Prep, #1 Test Prep

Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.

★★★★★5.0563 reviews
GMATLiveTeachStarts Nov 22
Josh Braslow, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Josh Braslow, 20+ years in test prep

Nov 22 · Josh Braslow
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemandStart anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

EXECUTIVE ASSESSMENT

with

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemandStart anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 563 reviewsTarget Test Prep

Need a time saving solution

Expert replies
Post new topic Post Reply
Subscribe topic
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 11
Joined: Mon Aug 25, 2008 1:52 am
by sabal » Mon Nov 24, 2008 1:41 am
The product of all the prime numbers less than 20 is closest to which of the following powers of 10?
A. 10^9
B. 10^8
C. 10^7
D. 10^6
E. 10^5

The OA is C

This question is from OG 11 Diagnostic Test Q. No. 15

Does anyone have any idea on how to solve this besides doing the usual 2*3*5*....... A method wherein I can save some time...?

Thanks!!
Top
Join the discussion
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pmFollowed by: 25 members
Thanked: 237 times
GMAT Score:730

Re: Need a time saving solution

by logitech » Mon Nov 24, 2008 1:58 am
sabal wrote:The product of all the prime numbers less than 20 is closest to which of the following powers of 10?
A. 10^9
B. 10^8
C. 10^7
D. 10^6
E. 10^5

The OA is C

This question is from OG 11 Diagnostic Test Q. No. 15

Does anyone have any idea on how to solve this besides doing the usual 2*3*5*....... A method wherein I can save some time...?

Thanks!!
first of all you do not have many numbers to deal with

2, 3, 5. 7. 11. 13. 17. 19

2 and 5 = 10

3 and 7 = 20

11 and 19 = 200

17 and 13 =200

so the multiplication is around 8 x 10 ^ 6 which is close to 10 ^ 7

The fast way to approximate your results.
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"
Top
Join the discussion