How many 4 digit nos that do not contain the digits 3 or 6 a

Oldest

Best Reply

Author

Message

TAGS:

Manager

Joined: 17 Sep 2011

Posts: 214

Followers: 0

Kudos [?]: 10 [0], given: 8

How many 4 digit nos that do not contain the digits 3 or 6 a [#permalink]

02 Feb 2012, 04:46

00:00

Question Stats:

0% (00:00) correct

0% (00:00) wrong

based on 0 sessions

How many 4 digit nos that do not contain the digits 3 or 6 are there ?

Actual solution states that the first digit has 7 possibilities which excludes 0,3,& 6. And the other 3 digits have 8 possibilities. So the total possibilities are 7 * 8 * 8 * 8==3584. This solution is perfect but why can't the other 3 digits have deceasing possibilities. The first digit has 7 possibilities. The second digit has 8 possibilities. So after selecting the second digit the third digit can have only 7 possibilities. similarly 4th digit could have 6 possibilities.

Why can't this be possible ? Could someone please clarify ?
_________________

_________________
Giving +1 kudos is a better way of saying 'Thank You'.

GMAT Club team member

Joined: 02 Sep 2009

Posts: 11521

Followers: 1795

Kudos [?]: 9547 [0], given: 826

Re: How many 4 digit nos that do not contain the digits 3 or 6 a [#permalink]

02 Feb 2012, 15:06

abhi47 wrote:

Because we are not told that the digits must be distinct hence they can repeat.

If it were: "how many 4-digit numbers are there which do not contain 3 or 6 and have all distinct digits?" then the answer would be - 7*7*6*5. The first digit can tale 7 values (except 0, 3, and 6), the second digit can take also 7 values (except 3, 6 and the one we used for the first digit), and so on.

Hope it's clear.
_________________

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!

What are GMAT Club Tests?
25 extra-hard Quant Tests

Find out what's new at GMAT Club - latest features and updates

Re: How many 4 digit nos that do not contain the digits 3 or 6 a [#permalink] 02 Feb 2012, 15:06

	Similar topics	Author	Replies	Last post
Similar Topics:	How many four digit numbers that do not contain the digits 3	NEWKID	2	09 Nov 2004, 07:19
	How many four-digit numbers that do not contain the digits 3	sperumba	5	17 Jan 2006, 18:09
	How many 3 different digit integer can be formed using 6	auniyal	7	15 May 2007, 11:52
	How many four digit integers do not contain any digits other	bmwhype2	6	15 Nov 2007, 07:50
	How many 5 digit nos are there if the 2 leftmost digits are	abhi47	2	02 Feb 2012, 04:59

How many 4 digit nos that do not contain the digits 3 or 6 a

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

How many 4 digit nos that do not contain the digits 3 or 6 a

How many 4 digit nos that do not contain the digits 3 or 6 a

Main navigation

GMAT Resources

Partners

MBA Resources