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#2 2012-12-22 05:33:17
- anonimnystefy
- Real Member
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Re: 4 digit no.
I have that abcd=2178.
The limit operator is just an excuse for doing something you know you can't.
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#3 2012-12-22 05:48:18
- bobbym
- Administrator
Online
Re: 4 digit no.
Hi;
Yes, and that is the only solution.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#5 2012-12-22 06:20:41
- bobbym
- Administrator
Online
Re: 4 digit no.
Hi;
First thing that jumps right out at you is that the front digit is either a 1 or 2. So, the last digit is a 4 or an 8. You now only have to try 16 numbers to find all the answers.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#6 2012-12-22 21:53:52
- phrontister
- Real Member
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Re: 4 digit no.
Hi,
a = 2...from d x 4 = even, and a x 4 must be a single-digit result (to avoid a 5-digit end product).
b = 1...from b x 4 must be a single-digit result (to keep a = 2), and 2 is already taken.
d = 8...from a x 4 = 8.
c = 7...from (c x 4) + the tens unit (3) from d x 4 must end in 1, which is only possible with c = 7 or 2; but 2 is already taken.
So, abcd is 2178.
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