Excel's PERCENTOF function returns the percentage that a subset of data contributes to a whole dataset, saving you from having to create additional or complex formulas to generate the same outcome.

When using chemical formula it is possible to calculate the percentage composition of the chemical. This can be useful when extracting metals from ores or when making fertilisers for specific plants.

Sure, there are other factors at play like how good the student is at that particular class, but we’re going to ignore confounding factors like this for now and work through a simple example ... and ...