prep #22

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 269
Joined: 01 Apr 2007

prep #22

by dunkin77 » Tue Apr 24, 2007 2:00 pm
Hi,

I thought the answer should be 10^2 but turned out to be 10 -- Can you please show me??
Attachments
pp22.JPG

User avatar
Community Manager
Posts: 789
Joined: 28 Jan 2007
Location: Silicon valley, California
Thanked: 30 times
Followed by:1 members

by jayhawk2001 » Tue Apr 24, 2007 9:17 pm
Compared to 10^8, 10^2 is a very small number. So, the difference
is approx 10^8

Similarly 10^7-10^3 is approx 10^7

So, the fraction boils down to 10^8/10^7 = 10

Legendary Member
Posts: 559
Joined: 27 Mar 2007
Thanked: 5 times
Followed by:2 members

by Cybermusings » Wed Apr 25, 2007 4:58 am
(10^8 - 10^2) / (10^7 - 10^3)

Take 10^2 common in the numerator
10^2 [ 10^6 - 1]
Take 10^2 common in the denominator also
10^2 [10^5 - 10]

So it becomes 10^2 [ 10^6 - 1] / 10^2 [10^5 - 10]
or 10^6 - 1 / 10^5 - 10
or 1000000-1 / 100000 - 10
or 999999/99990
Approximately 10