First, you have to show your work. I really don’t care if you get the right numerical value at the end. I care to see that you can show me you know what you are doing. Be very clear and careful presenting your solution. Start from fundamental things. Don’t start with some whacked out equation that you found on the floor.
Second, units. Every time you don’t put units on your answer, a little part of me dies. I don’t want to die.