In October 2012, Microsoft released a new version of Microsoft Office Mobile for Windows Phone 8 and Windows Phone 7.8. This was followed up by the release of Office Mobile for iPhone on 14 June 2013, and Office Mobile for Android phones on 31 July 2013.
That's an easy number to work with, so let's use it. 20 drops/milliliter = 20,000 drops/liter =1,000,000 drops / 50 liters. That means one part per million is the same as one drop of a substance in a million drops, or 50 liters, of water.
The prefix in front of the unit tells you how to move the decimal. 1 milliliter = 0.001 liters because milli means thousandth. 1 thousandth of a liter = 0.001 liters. 0.1 liters is 100 times as much as 0.001 liters. Therefore 0.1 liters = 100 ml. Since each ml of water weights 1 g, 0.1 liters of water = 100 grams.