To perform this conversion first you will need to consider that each PPM of CO, recorded at Mauna Loa in a particular year can be assumed to represent one million (10") molecules to CO2. Before we use the number of PPM recorded in one year in our calculations we need to "scale it down" - so that each PPM represents only one molecule. Insert the results of this calculation in column C (PPM Reduced). Notice that the cells in column C have been formatted to show eight decimal digits (if you only see zeros, then your formatting is wrong and you need to reformat the cells = ). Leave blank all the cells that correspond to the years (from 2016 to 2039) where you have no data