No repeated digits: 100-999

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Fahim Shahriar
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No repeated digits: 100-999

Unread post by Fahim Shahriar » Sun Apr 15, 2012 1:53 pm

How many 3 digit positive integers have no repeated digits. :) ;) :)
Name: Fahim Shahriar Shakkhor
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sm.joty
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Re: No repeated digits: 100-999

Unread post by sm.joty » Mon Apr 16, 2012 12:40 am

$9*9*8$
But it will be quite more interesting if you want to find the sum of these numbers. ;)
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Phlembac Adib Hasan
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Re: No repeated digits: 100-999

Unread post by Phlembac Adib Hasan » Mon Apr 16, 2012 9:14 am

Yes, yes.So I am requesting you post it as a new topic.
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sakibtanvir
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Re: No repeated digits: 100-999

Unread post by sakibtanvir » Thu May 31, 2012 9:01 pm

After summing it would be 287712..........isn't it?
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Masum
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Re: No repeated digits: 100-999

Unread post by Masum » Wed Jun 06, 2012 3:50 pm

তোমার পদ্ধতিটা দেখাও। কারণ অনেক সময় ভুল করেও ঠিক উত্তর পাওয়া যায়।
One one thing is neutral in the universe, that is $0$.
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sakibtanvir
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Re: No repeated digits: 100-999

Unread post by sakibtanvir » Wed Jun 06, 2012 9:41 pm

Vaia,vul koreo thik ans pawa jay!!!Bishoyta ektu clear korben ami thik bujhi nai :? Amar solution ta dilam.
Lets Find the number of all numbers whose 1st digit is 1 (where is no repetation obviously)
Thare are $9*8=72$ such numbers.Again there are 72 numbers with the first digit 2.Each time there are 72 numbers with the first digit $n$ .$(n=1,2,3,4.....,9)$
There are 72 numbers whose middle digit is $n$ .$(n=1,2,3,4.....,9)$(No need to count zeroes...)
We can apply the same method for the last digits.......
So, after adding them, the summation would be $72(1+2+3+...9)10^{2}+72(1+2+...9)10+72(1+2+...9)=359640$
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sakibtanvir
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Re: No repeated digits: 100-999

Unread post by sakibtanvir » Wed Jun 06, 2012 9:49 pm

Amar ager ans ta vul chilo....tarahura kore koray vul hoiche..keu notice kore nai. :lol:
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sm.joty
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Re: No repeated digits: 100-999

Unread post by sm.joty » Wed Jun 06, 2012 11:06 pm

sakibtanvir wrote:Amar ager ans ta vul chilo....tarahura kore koray vul hoiche..keu notice kore nai. :lol:
দেখছিলাম কিন্তু রিপ্লাই দেয়ার টাইম পাই নাই। যাইহোক তোমার মেথড টা ঠিকাছে। এটাকে জেনেরালাইজ কর আরও অনেক মজার জিনিস পাবা। আর এইটা নিয়ে আরও জোস প্রব্লম আছে। আমি কোন জায়গায় জানি দিসিলাম। এই ফোরামেই।
খুজে দেখ। জোস সমস্যা। :D
হার জিত চিরদিন থাকবেই
তবুও এগিয়ে যেতে হবে.........
বাধা-বিঘ্ন না পেরিয়ে
বড় হয়েছে কে কবে.........
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Masum
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Re: No repeated digits: 100-999

Unread post by Masum » Thu Jun 07, 2012 11:12 am

sakibtanvir wrote:Vaia,vul koreo thik ans pawa jay!!!
viewtopic.php?f=19&t=2217
One one thing is neutral in the universe, that is $0$.
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