Harry wants to bake a small cake so he uses 1 cup of sugar based on the recipe how many cups of flour should he use

Depending on the size of the small cake it probably needs about 2 cups of flour to add to the mix. If I am not right, try it out at home, and just see what your result is.

I think that Harry should use 1.5-2 cups of flour for his cake. It depends on the size of the cake so if its pretty small, 1.5 cups should work. If you want to take a risk, use more cups of flour.