Step-by-step explanation:
1 kg = 1000 grams (hence the name : "kilo" means 1000).
so, 2kg = 2×1000 = 2000 grams.
now, how many CDs are in 2000 grams, when 1 weighs 10 grams ?
in other words : how often does 19 grams fit into 2000 grams ?
that is what division is for :
2000/10 = 200
so, you would need 200 CDs to reach 2kg.
