Unit analysis is a form of proportional reasoning where a given measurement can be multiplied
by a known proportion or ratio to give a result having a different unit or dimension.
Algebraically, we know that any number multiplied by one will be unchanged.
If the number has units, and we multiply it by a ratio containing units, the units in the number
will multiply and divide by the units of the ratio, giving the original number but with different
This method can be generalized as: multiply or divide a given number by a known ratio to find
The ratios used are based upon the units and are set up so that the units in the denominator of
the ratio match the numerator units of the given and the units in the numerator of the ratio
match those in either the next ratio or the final answer.
When these are multiplied, the given number will now have the correct units for your answer.
Say you were trying to convert 3.41 grams of He to a number of atoms of He. You would