About factorial��

This topic has expert replies
Newbie | Next Rank: 10 Posts
Posts: 1
Joined: Mon Mar 07, 2011 9:46 pm

About factorial��

by 327356719 » Mon Mar 07, 2011 9:50 pm
a^99! that's mean a^1*a^2*....*a^99 or [(a^1)^2.....]^99???


The question confuse me a lot! thaks!

Master | Next Rank: 500 Posts
Posts: 423
Joined: Fri Jun 11, 2010 7:59 am
Location: Seattle, WA
Thanked: 86 times
Followed by:2 members

by srcc25anu » Mon Mar 07, 2011 9:51 pm
in my opinion it means a^(1*2*3*....99)

Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pm
Thanked: 127 times
Followed by:10 members

by Night reader » Mon Mar 07, 2011 9:57 pm
no, it's when you multiply a 99! times --> a*a*a*a*a*a*a*a*... a (total 99! times)
can be further rewritten as (a^98!)^99 OR (a^97!)^(98*99)
327356719 wrote:a^99! that's mean a^1*a^2*....*a^99 or [(a^1)^2.....]^99???


The question confuse me a lot! thaks!
My knowledge frontiers came to evolve the GMATPill's methods - the credited study means to boost the Verbal competence. I really like their videos, especially for RC, CR and SC. You do check their study methods at https://www.gmatpill.com

User avatar
GMAT Instructor
Posts: 905
Joined: Sun Sep 12, 2010 1:38 am
Thanked: 378 times
Followed by:123 members
GMAT Score:760

by Geva@EconomistGMAT » Tue Mar 08, 2011 2:40 am
Night reader wrote:no, it's when you multiply a 99! times --> a*a*a*a*a*a*a*a*... a (total 99! times)
can be further rewritten as (a^98!)^99 OR (a^97!)^(98*99)
327356719 wrote:a^99! that's mean a^1*a^2*....*a^99 or [(a^1)^2.....]^99???


The question confuse me a lot! thaks!
Could actually mean either way, depending on whether the '!' sign is part of the exponent or not. If the ! sign is in the exponent superscript, then Night reader's interpretation is correct: we first deal with the exponent (i.e. figure out what is 99!), then multiply a by itself that huge number of times.
If the '!' sign is not part of the exponent, then we first figure out the power a^99, then make THAT number factorial.
Geva
Senior Instructor
Master GMAT
1-888-780-GMAT
https://www.mastergmat.com