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A palindrome number is a number that is the same forwards as backwards. Some examples are 3443, 12321, and 59095.

Here's my question: What is the largest 12 digit palindrome that is evenly divisible by 7?

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Vote to close as a math Q – ghosts_in_the_code Jan 2 at 10:52
up vote 12 down vote accepted

It would appear that the largest 12 digit number, 999,999,999,999 is divisible by 7 and is also a palindrome. So that must be the largest 12 digit palindrome divisible by 7

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up vote 7 down vote

999,999,999,999 as Stephen mentioned is divisible by 7. Just for fun, here are the next nine largest ones:

999992299999
999989989999
999982289999
999979979999
999972279999
999969969999
999962269999
999959959999
999952259999

If we're not allowing for repeated digits in each half, the largest ten would be:

987654456789**
987634436789
987624426789
987614416789
987604406789
987563365789
987543345789
987523325789
987513315789
987503305789

** = I just find it interesting that in both cases, the largest acceptable answer is unaffected by the "divisible by 7" clause.

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