400
When Spencer was a baby elephant he weighed 2,000 kilograms (kg), now that Spencer is an adult he weighs 6,000 kilograms. How much weight has Spencer gained, in grams?
6,000 kg - 2,000 kg = 4,000 kg gained
1 kg= 1,000 g so
4,000 kg x 1,000 g= 4,000,000 g
Spencer gained 4 million grams of weight.