∵ Each tablet weighs = 20 mg
∴ The weight of 2,00,000 tablets = 2,00,000 × 20 = 40,00,000 mg
∴ The total weight of all the tablets in the box = 40,00,000 mg
We know 1 g = 1,000 mg
∴ Weight of the box having all tablets = 40,00,000 ÷ 1,000 = 4,000 g
And, as 1 kg = 1,000 g
∴ Weight of the box having all tablets = 4,000 ÷ 1,000 = 4 kg