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20110917, 13:13 #1
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Finding the largest 4digit integer
What is the greatest fourdigit integer that meets the following three restrictions?
1. All of the digits are different.
2. The greatest digit is the sum of the other three digits.
3. The product of the four digits is divisible by 10 (no remainder) and not equal to zero.Last edited by kweaver; 20110917 at 13:16. Reason: adjustment

20110917, 14:49 #2
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Best I can do is
BATcher
Mission: identify what we do best and find more ways of doing less of it better

20110917, 15:33 #3
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You have it correct. Did you try trial&error, logic or algebra or some combination? Just curious.

20110918, 03:48 #4
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Just logic, really. The only way of getting something divisible by 10 is to have the product digits being 2 and 5  no others will work. Since all the digits must be different, then the other one had to be 1, thus the largest must be the sum of these, 8. If you had 9, the 'other' digit would then have had to be 2  and we have used 2 already...
I'm not any good at puzzles!BATcher
Mission: identify what we do best and find more ways of doing less of it better

20130214, 00:05 #5
BATcher You are a Genius .