6.1. Find the largest six-digit number, all digits of which are different, and each of the digits, except for the extreme ones, is either the sum or the difference of the adjacent digits.
Answer: 972538.

Solution. Let $A$ be the desired number. Let's try to find the number $A$ with the first digit being 9. We will try different options for the second digit. If the second digit is 8, then we get: $A=98176-$ it does not form a six-digit number. If the second digit is 7, then we get: $A=972538-$ a six-digit number.

Comment. Just the correct answer, but attempts to find the maximum number are missing - 4 points.

Any incorrect answer - 0 points.