How many 5-digit numbers can be formed from the digits 1, 2, 3, 4, 5, 6, 7, 8, 9?
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Math Expert Joined: 02 Sep 2009 Posts: 87762 How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, [#permalink] 01 Mar 2021, 04:46
00:00 Question Stats: 87% (00:42) correct 13% (00:39) wrong based on 45 sessions Hide Show timer StatisticsHow many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, 9 if no digit can be used more than once in a number ? A. 120 _________________ CrackVerbal Representative Joined: 03 Oct 2013 Affiliations: CrackVerbal Posts: 4988 Location: India Re: How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, [#permalink] 01 Mar 2021, 05:13 Basically the question is asking how many 5 digit numbers can be formed without repetition. If we do by the box method, then the 1st place can be filled in 6 ways, second in 5, 3rd in 4 4th in 3 and the last in 2 ways. Total number of ways = 6 * 5 * 4 * 3 * 2 = 720 In terms of permutations, we need to arrange 5 digit out of 6 = 6P5 = 6! / (6 - 5)! = 720 ways In terms of combinations, first choose 5 numbers out of 6 in 6C5 ways and then arrange these 5 digits in 5! ways. Total arrangements = 6C5 * 5! = 6 * 5! = 720 Option D Arun Kumar GMAT Club Legend Joined: 08 Jul 2010 Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator Posts: 5914 Location: India GMAT: QUANT EXPERT WE:Education (Education)
How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, [#permalink] 01 Mar 2021, 06:28 Bunuel wrote: How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, 9 if no digit can be used more than once in a number ? A. 120 We have 5 empty places like this - - - - - We have 6 digits to use and the digit can NOT be repeated Method-1 So we can fill the first place in 6 ways 6 - - - - So we can fill the Second place in 5 ways (can not use the used digit at first place) 6 * 5 - - - So we can fill the Third place in 4 ways (can not use the used digits at previous places) 6 * 5 * 4 - - So we can fill the Forth place in 4 ways (can not use the used digits at previous places) 6 * 5 * 4 * 3 - So we can fill the Fifth place in 4 ways (can not use the used digits at previous places) 6 * 5 * 4 * 3 * 2 So total numbers = 720 ANswer: Option D Method-2 Step-1: Select 5 out of 6 digits that need to be used to make a five digit number in \(^6C_5\) ways 5! ways Total Such numbers = \(^6C_5*5! = 720\) ANswer: Option D Two MUST join YouTube channels for GMAT aspirant GMATinsight (1000+ FREE Videos) and GMATclub For a Comprehensive Topicwise Quant Video course at an affordable price CLICK HERE _________________ GMATinsight Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 11711 GPA: 3.82 Re: How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, [#permalink] 01 Mar 2021, 08:02 Total numbers: 6 [2, 3, 5, 6, 8, 9] Condition: Repetition not allowed Five-digit number: _, _, _, _, _ For first place from left, we have the choice of 6 numbers => 6 * 5 * 4 * 3 * 2 = 720 Answer D Re: How many 5-digit numbers can be formed from the digits 2, 3, 5, 6, 8, [#permalink] 01 Mar 2021, 08:02 Moderators: Senior Moderator - Masters Forum 3098 posts How many 56×6×5×4×3 = 2160 five digit numbers can be formed.
How many 5Total Number of Numbers which can be formed by numbers 1,2,3,4,5 (without repeating digitsi) = 5*4*3*2*! = 5! = 120.
How many 5When the digits are 2, 4, 5, 6, 7. the last two digits possible for the number to be a multiple of 4 are 24, 64, 52, 72, 56, 76. For each of these combinations, there are 6 different numbers possible. So, with this set of 5 digits we can have 36 different numbers.
How many 5So the total number of ways to form a 5-digit number =4×5×5×5×5=2500.
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