This bug deals with the lack of checking when doing operations on cards. It is quite simple; let me walk you through.
Select one card.
Select another card.
In some cases subtraction causes negative numbers. In this case, I will divide and get a number that... doesn't quite exist in cards. The result; after dividing? Check it out:
Yeah... not quite right.
The big problem? The checking algorithm counts these as valid steps to a solution! This means that unreasonable or unintuitive answers are considered right by the checking algorithm!