How to solve puzzle 81 (the old safe) in Professor Layton and the Diabolical Box?

i know you can look up the answer to puzzle 81/the old safe in professor layton and the diabolical, but can someone explain how to solve it? i don't understand how the lights give you the numbers 0154...|||its like a puzzle i had when i was a kid. you plug in 4 numbers and get lights depending on the answer. White light means you have a number right but in the wrong place. Orange means you have a number right and in the right place. For example the code is 0154 if i put in 0123 i'd get 2 orange lights meaning i got 2 numbers right (the 0 and 1) in the right spot. If i put in 4321 i'd get 2 white lights meaning i got 2 numbers right (the 1 and 4) but in the wrong place.