After the 7th puzzle, head to the southern room on the top floor. This is by far the absolute dumbest possible puzzle and tells you absolutely everything you need to know about this game.
"The solution is on the back of the box of a different game."
so essentially, you have no way of figuring it out through trial and error (with 10,000 possible combinations) or looking it up online.
The answer is: 140 15