The first five homologues are generated by adding one – CH_{2} – at a time, starting with the first homologue, methane (CH_{4}).

By counting carbon and hydrogen atoms in the five homologues, we get their molecular formulae as CH_{4} , C_{2} H_{6} , C_{3} H_{8} , C_{4} H_{10} and C_{5} H_{12} . Comparing these molecular formulae and assigning the number of carbon atoms as ‘n’, the following general formula is deduced: C_{n} H_{2n + 2}