* Know that 1 kg = 1000 g

* Set up a proportion: 200g / 1000g = x / 100%

* Solve for x: Cross-multiply to get 200g * 100% = 1000g * x

* Simplify: 20000 = 1000x

* Isolate x: Divide both sides by 1000: x = 20%

Therefore, 200g is 20% of a kilogram.