Describe a simulation used to determine a game of darts.

In the game of darts, you can hit each of the numbers from 1 to 20. Your score is doubled by landing in the outer ring and trebled if it lands in the inner ring. You score 25 by hitting the outer bull's eye and 50 by hitting the bull's eye. A person can throw 3 darts. How many scores are not possible to achieve with 3 darts between 1 and 180 (all three of the darts must be used, and ignore the rule about finishing with a double)?

I know that 2 obvious ones would be 1 and 2, but other ones aren't as obvious. It would take too long to try if it is possible for 180 numbers, so is there an equation to do this?

I reckon I could get a score of 1. 2 in the wall and one on the board!

i think it might be a but you might want a second opinion