1.2.1 Study Note 1
Simple rules for dealing with orders of magnitude and decimal points in decimal numbers: values ten times bigger than the order of magnitude you are looking at go to the left, ten times smaller go to the right, and less than 1 to the right of the decimal point.
Note: in many European countries, a comma is used instead of a decimal point. For instance in France and Germany two and a half (in other words 2.5) can be written as 2,5. This is important to bear in mind, for example, if the drug you are measuring out comes from a European supplier, or you are following a laboratory protocol that was developed abroad.