Asked by Winston

A shirt button gas a mass of 400 mg. A factory produces a tonne of these buttons in a year. How many buttons does it produce.
Henry
400mg = 0.400g = 4.00*10^-4 kg.

1 tonne = 1000kg.

1000/4*10^-4 = 2.5*10^6 = 2.5 Million buttons.