There is a chart you could use it goes like this:
Kilo-1,000
Hecto-100
Deka-10
Meter/liter/gram-1
Deci- 1/10 or 0.1
Centi- 1/100 or 0.01
Milli- 1/1000 or 0.001
To convert up the chart you divide by ten and to convert down the chart you multiply by ten. So if you have 1 kilogram, work your way down the chart until you get to grams. Make sure you multiply the one by 10 each time you step down.