Answer :
1 kg=1000g*1000mg/1g=1000000mg =10⁶ mg
or you can use proportion
1000g - x mg
1 g -1000mg
x=1000*1000=1000000mg
1kg=10⁶ mg
or you can use proportion
1000g - x mg
1 g -1000mg
x=1000*1000=1000000mg
1kg=10⁶ mg