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        riddles >> easy >> 2-digit Parade
        
(Message started by: Sir Col on Nov 28th, 2008, 11:01am)
Title: 2-digit Parade
Post by Sir Col on Nov 28th, 2008, 11:01am
By selecting a single digit from the 5-digit number, 12345, it is possible to obtain five 1-digit numbers: 1, 2, 3, 4, and 5.

By selecting two digits from the same 5-digit number, 12345, it is possible to form twenty 2-digit numbers: 12, 13, 14, 15, 21, 23, 24, 25, 31, 32, 34, 35, 41, 42, 43, 45, 51, 52, 53, and 54.

a) Find the smallest positive integer that contains every 1-digit number.

b) Find the smallest positive integer that can be used to form every 2-digit number (10 to 99).
Title: Re: 2-digit Parade
Post by 0.999... on Nov 28th, 2008, 1:45pm
a) lim n->http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/infty.gif123456789/10n
b) lim n->http://www.ocf.berkeley.edu/~wwu/YaBBImages/symbols/infty.gif112233445566778899/10n
Title: Re: 2-digit Parade
Post by Sir Col on Nov 28th, 2008, 2:36pm
Sorry, I should have said, "Find the smallest positive integer...". I've edited the problem wording.


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