Yes, but the concentration needs to be in g/mL. When I did it that way, my excel sheet said my answer was correct. Thats how my teacher explained to get concentration. But she has me confused when I want to find the concentration containing 2.00 mL of stock solution.

2.05 X 10 ^ -4 is the concentration I got for my stock solution. I divided that by 10 mL to get 0.000205 g/mL .