How do I convert 10 percent CO2 to parts per million CO2?

Parts per million is a fraction with denominator 1,000,000. For example 5 parts per million means 5/1,000,000. Percent is a fraction with denominator 100. For example, 5 percent is 5/100. So your...

-- take the number of parts per thousand -- multiply it by 1,000 -- the answer is the number of parts per million

One milligram per kilogram IS one part per million: There are 1,000 milligrams in one gram and 1,000 grams in one kilogram. 1,000 mg = 1 g 1,000 g = 1 Kg 1,000 x 1,000 = 1,000,000

There are several ways to go about this. If you want to determine ppm of a solute in water for example, you can determine the number of grams of water in 1 L by its density (1.0 g/mL=1000.0 g/L)....

If you have 1 million parts of something 10 parts would be 10 parts per million. If you had 2 million parts of something 20 parts would be 10 parts per million.