I hope I am not too late! :P
500 individuals boxes! NO, too effort!
2 marks usually mean worth 2 minutes or so...thus the method must be quick/easy
Instead of counting individual box
Do this:
Therefore each boxes = 500 x 0.2x10^-3 = 0.1N.s
so here there is 16 complete boxes
what about the uncompleted boxes? well using your own judgement, how much complete boxes can be made from those pieces?
For me I say maybe 4-6 boxes but Im going to go with 4...
4+16 = 20 boxes
20 ( 500 x 0.2 x10^-3) = 2Ns
MS: 2.2 Ns {allow 2.0 to 2.4}