Mathematics works also even if it can't be translated into materialistic reality. You can have negative numbers but you can't eat a negative cookie.
Mathematics serves the purpose of representing the world around us. It progresses a lot slower than science because everything needs to be empirically proven beyond doubt before moving on.
[quote]But try to do the opposite. How will your example work if you have 8 cookies lying on your table and you multiply them with 0?[quote]
You have eight cookies in one row, multiplication sets the number of rows, 1 (multiply by 1) row still equals 8 cookies, Multiplying by zero gives you zero cookies, it's a certain thing, zero rows of cookies.
Also, you can eat negative cookies. Two words, gag reflex.