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Let X be a set of all 13 digit Integers where each digit can take values from 0 to 9 . An Integer is choosen at random from X
. then find the probability that it is a palindrome
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Can the 1st and 13th digit be only 1 to 9, or can they be zeros.
I only like this problem if the 0 is included due to the symmetry of the problem.
But then it might not be an Integer.
Is 0000007000000 a good example of an allowable Integer in this problem?
igloo myrtilles fourmis
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Oh, I just thought of the answer.
Pair up the mirrored digits and you get:
10 times 10 times 10 times 10 times 10 times 9 if no zero allowed on end.
igloo myrtilles fourmis
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do you see why that works.
See this:
ABCDEFQFEDCBA
The A can be 0 to 9.
The B,C,D,E,F can to 0 to 1 to 9, or ten of them.
Get it? Happy new year. Bonne nouvelle ans!!
igloo myrtilles fourmis
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hi John
i have a little problem with what you wrote there.
if those are 13 digit numbers,then A cannot be 0 so it goes from 1 to 9.so it will be:
9*10*10*10*10*10*10=9*(10)^6
Last edited by anonimnystefy (2012-01-01 08:48:16)
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Hi juan and all;
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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bobbys right!
I meant 1 to 9 for A.
igloo myrtilles fourmis
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thanks bobbym and anonimnystefy and Franklin
and belated happy new year 2012
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Hi juantheron;
You are welcome, glad to help.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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