First of all, this isn't physics. But, here's the answer:
1 gram is a 1000 milligram and 250 milligram is 250 * 0.001 g which is 0.25 gram.
Since 1 kg is 1000 g, we divide 1000 by 0.25 and we get 1000 * 4 which is 4000.
There are [tex]4000[/tex] tablets inside the bottle.
