[jameshart]

Knowing that a bijection exists between states and stars on the US flag, first obtain a US flag. Observe that the stars in the top left corner fall in a rectangular n x m grid with stars located at every node, and also in the rows and columns in between, forming a smaller (n-1) x (m-1) rectangle, so the number of stars is nm + (n-1)(m-1). Then you can just count n and m - 6 and 5 respectively - and substitute to obtain 30+20=50 stars.