4 Digit Positive Integers

Expert replies

Previous Topic Next Topic

hatterhero: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Tue Aug 25, 2009 6:26 pm

by hatterhero » Tue Aug 25, 2009 6:27 pm

How many 4-digit positive even integers are there?

Like this post

Source: Beat The GMAT — Problem Solving | Tue Aug 25, 2009 6:27 pm

keough: Junior | Next Rank: 30 Posts; Posts: 10; Joined: Tue May 06, 2008 10:44 pm; Thanked: 1 times

by keough » Tue Aug 25, 2009 6:42 pm

Smallest 4 positive even integer is 1000
Largest 4 digit positive even integer is 9998

Therefore total integers (9998 - 1000)/2 + 1 = 4500

Like this post

rish: Senior | Next Rank: 100 Posts; Posts: 65; Joined: Fri Jul 24, 2009 11:47 am; Thanked: 5 times

by rish » Tue Aug 25, 2009 7:48 pm

Here is another method

since you want only even numbers, the last digit can be 0,2,4,6,8. Number of ways of choosing one digit out of these is 5C1 = 5

1st digit can be 1..9 (excluding 0)..so number of ways = 9C1=9

2nd digit can be 0..9..so number of ways =10C1=10
3rd digit can be 0..9..so number of ways =10C1=10

So total = 9*10*10*5 = 4500

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review