Answer :

iGreen
1 gram = 1000 milligrams

72 * 1000 = 72000

So 72 grams is equal to 72,000 milligrams.
Lemony
You know that 1 gram = 1000 milligrams

So then you set up a proportion to find how much mg does 72 grams equal to.

1 gram = 1000 mg
72 grams = x mg

Then cross multiply

x = 1000 times 72
x = 72000

Answer: 72,000 mg