The central issue in converting units in the SI system is to figure out how many small units equal one big unit. Here is how to do it:
Take a conversion from millimeters to kilometers. Look at the power of ten next to kilo- in the chart: 103. Now look at the power of ten next to milli- in the chart: 10-3. Divide the power of ten next to the larger unit by the power of ten next to the smaller unit:
103 ———— = 106 (when dividing numbers raised 10-3 to an exponent, subtract exponents) 1 x 106 mm 1 x 106 mm = 1 km or ———————— 1 km
This result says that there are 106 (1,000,000) millimeters in 1 kilometer. Try another one: how many nanometers (the smaller unit) are there in 1 centimeter (the larger unit)? Nano- is 10-9 and centi- is 10-2.
10-2 ———— = 107 or 10,000,000 So there are 1 x 107 (10,000,000) nm in 1 cm. 10-9
How many mL are there in one L? base 100 ————— = 103 which means 1 L = 1,000 mL milli- 10-3 How many pg are in one μg? μ- 10-6 ————— = 106 which means 1 μg = 1,000,000 pg pico- 10-12 Now convert 5,897,000 pg to μg: 1 μg 5,897,000 pg × —————————— = 5.897 μg 1,000,000 pg