Original house number: 139.
Alternate house number: 126
Conversion: 139 - (1 + 3 + 9) = 126; original number minus the sum of its digits.
Original house number: 222
Alternate house number: 8
Conversion: 2 * 2 * 2 = 8; digits of original number multiplied.
The task is to write a piece of code that helps to find the conversion, based on the original number, the alternate number and a set of rules. You can choose the rules as you like and extend them gradually. You can start with + and - operations on the original number and its digits. You can take multiplication into account, as in the second example. You can choose to apply division. You can restrict the rules to always use all of the digits or extend them to use any combination of the digits, with or without repetitions. The program may give an exact answer, or simply answer "conversion unknown", in some cases.