Known nine digits "2007? 12? 2 "is both a multiple of 9 and a multiple of 1 1, so what is this nine-digit number? A multiple of 9. The sum of each number is a multiple of 9.

therefore

The sum of these two digits plus 14 is a multiple of 9.

So the sum of these two digits is 4 or 13.

1 1 The difference between the sum of numbers on odd digits and the sum of numbers on even digits is a multiple of 1 1.

therefore

The difference between these two numbers is 2.

therefore

This nine-digit number is

20073 12 12

I saw it from somewhere else.