Last visit was: 09 Jul 2025, 13:05 It is currently 09 Jul 2025, 13:05
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
Ekland
Joined: 15 Oct 2015
Last visit: 30 Apr 2023
Posts: 359
Own Kudos:
841
 [1]
Given Kudos: 342
Concentration: Finance, Strategy
GPA: 3.93
WE:Account Management (Education)
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 09 Jul 2025
Posts: 11,296
Own Kudos:
41,639
 [2]
Given Kudos: 333
Status:Math and DI Expert
Products:
Expert
Expert reply
Posts: 11,296
Kudos: 41,639
 [2]
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
JhonnyMe
Joined: 07 Dec 2024
Last visit: 07 Jul 2025
Posts: 15
Own Kudos:
Given Kudos: 124
Posts: 15
Kudos: 8
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 9 July 2025
Posts: 102,609
Own Kudos:
739,889
 [1]
Given Kudos: 97,813
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,609
Kudos: 739,889
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
JhonnyMe
chetan2u
Ekland
If \(P = 478+477!+476!\), which of the following must have a remainder when it divides into P?

I. \(239\)
II. \(10+9\)
III. \(5!-90\)


A. I only
B. II only
C. III only
D. I and II only
E. II and III only


\(478+477!+476!=478+476!(477+1)=478+478*476!=478(1+476!)\)

Now, 476! is product of all numbers till 476, so when we add 1 to 476!, the number is not divisible by all numbers till 476.
So 478(1+476!) will not be divisible by any number till 476 except the factors of 478 that are 2 and 239.


I. \(239\).....478=2*239, so the number is divisible by 239
II. \(10+9\)=19.....19 is not a factor of 478 and is less than 476. Thus it will leave a remainder
III. \(5!-90\)=120-90=30.... .19 is not a factor of 478 and is less than 476. Thus it will leave a remainder

II and III

E
Hey, thank you for the explanation! Why is 1+476! not divisible by any number equal to or less than 476?

I can see how 476! will have a few tailing 0's. And adding a 1 to this makes it an odd number, and can be a prime too. But not sure how to prove the above statement.
476! and 476! + 1 are two consecutive integers, which means that they do not share any factor other than 1. For example, 20 and 21, being consecutive integers, do not share any factor other than 1 (they are co-prime).

Since 476! is divisible by all numbers less than or equal to 476, then 476! + 1 won't be divisible by any number less than or equal to 476.
Moderators:
Math Expert
102609 posts
PS Forum Moderator
683 posts