10.how many two‐digit odd numbers can be formed from 0 – 9 if repetition of digits is not allowed?
|
$\begingroup$ Show
My attempt is as follows:
Even four-digit numbers $> 4000$: $$ 3 \times 6 \times 5 \times 4 = 360 $$ Even four-digit numbers between $3500$ and $4000$: $$ 1 \times 2 \times 4 \times 5 = 40 $$ Answer: $$ 40 + 360 = 400 $$
asked May 22, 2017 at 13:20
$\endgroup$ $\begingroup$ I agree with your approach but not with your calculations. The simplest way seems to be to choose the digit of thousands first, then of units, then of hundreds and tens. $\rightarrow$ 4-digit even numbers between 3500 and 3999:
Hence $1*(3*2*4+1*1*4)=28$ numbers $\rightarrow$ 4-digit even numbers bigger than 4000, starting with 4 or 6:
Hence $2*3*5*4=120$ numbers $\rightarrow$ 4-digit even numbers bigger than 4000, starting with 5:
Hence $1*4*5*4=80$ numbers Total: $28+120+80=228$ answered May 22, 2017 at 13:31
 EvargaloEvargalo 2,5835 silver badges8 bronze badges $\endgroup$ As the title said, I have an assignment where we are asked: How many 2-digit numbers can be formed from even-numbered digits if the repetition of the digit is not allowed? I've tried answering it myself but I am not sure if it's correct. What I did was multiply 4 by 3, since there are 4 even-numbered digits (2, 4, 6, 8). And since repetition is not allowed, for the ones digit, I did 4 since nothing has been used yet and for the tens digit I only used 3 since one digit has been used before. Please correct me if I'm wrong. Sorry if my explanation is bad, I have a hard time trying to explain things and this is my first time posting. Many thanks! Edit: Okay, just a quick update. I asked my teacher and apparently, both 12 and 16 are considered answers. Case closed! :) Solution : Since each number is less than 1000, required numbers are the 1-digit, 2-digit and 3-digit numbers. GMAT Club Daily PrepThank 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 we will pick new questions that match your level based on your Timer History Track every week, we’ll send you an estimated GMAT score based on your performance Practice 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.Hello Guest!It appears that you are browsing the GMAT Club forum unregistered! Signing up is free, quick, and confidential. Join 700,000+ members and get the full benefits of GMAT ClubRegistration gives you:
and many more benefits!
Math Expert Joined: 02 Sep 2009 Posts: 86775 How
many two digit odd numbers can be formed from the digits 1, 2, 5, [#permalink]
00:00 Question Stats:
Hide Show timer StatisticsHow many two digit odd numbers can be formed from the digits 1, 2, 5, 6 and 7, if the repetition of digits is allowed ? (A) 12 _________________ Math Expert Joined: 02 Aug 2009 Posts: 10540
Re: How many two digit odd numbers can be formed from the digits 1, 2, 5,
[#permalink] Bunuel wrote: How many two digit odd numbers can be formed from the digits 1, 2, 5, 6 and 7, if the repetition of digits is allowed ? (A) 12 Let the number be XY, where X and Y are digits. B Scoreleap Test Prep Representative Joined: 07 Mar 2021 Posts: 241 Re: How many two digit odd numbers can be formed from the digits 1, 2, 5, [#permalink]
Given digits = 1, 2, 5, 6 and 7 Let us make two
blanks first: For a number to be odd unit place must be 1, 3 or 7 = 3 possibilities. Total two digit odd numbers = 5 * 3 = 15. So, correct answer is option B. Re: How many two digit odd numbers can be formed from the digits 1, 2, 5, [#permalink] 13 Mar 2021, 02:26 Moderators: Senior Moderator - Masters Forum 3084 posts How many 2 number combinations are there in the numbers 0 to 9?This means there are 90 possible combinations of two numbers using digits 0 through 9 if a digit cannot be repeated.
How many 2 digit numbers using the digits 0 to 9 can be formed that are divisible by 5?The correct answer is 41. Therefore by Multiplication principal, There are 32 such numbers.
How many 3Hence, by the fundamental principle of multiplication, the required number of odd numbers `= (3xx6xx6) = 108. ` How many two digit numbers can be made from the digits 1 to 9 if repetition is allowed?81 possible two digit numbers.
|
