It works because even if the numbers are broken apart, you are still multiplying the numbers by their values, it's only different because once broken apart, it's in expanded form instead of standard form. It also makes multiplication easier since you don't have to deal with such large numbers.
Answer:
30
Step-by-step explanation:
if you take 3+6+9+12 you get 30
3.75.....rounded to the nearest dollar would be 4.00
