It is known that a two digit ten digit number is one less than a single digit number. If the ten digit number is exchanged with a single digit number, the product of the new two digit number and the original formula is 405 more than the square of the original number, and the original number is——————

It is known that a two digit ten digit number is one less than a single digit number. If the ten digit number is exchanged with a single digit number, the product of the new two digit number and the original formula is 405 more than the square of the original number, and the original number is——————

Let X be the number above two digits, then the number above ten digits is (x-1). According to the meaning of the question, the equation is: 10x + (x-1) [10 (x-1) + x] - [10 (x-1) + x] & sup2; = 405 (11x-1) (11x-10) - (11x-10) & sup2; = 405 (11x-1-11x + 10) (1