The general formula for alkanes is C_nH_2n+2, where 'n' represents the number of carbon atoms in the alkane molecule.

Here's how it works:

* C_n: This part indicates the number of carbon atoms in the molecule.

* H_2n+2: This part indicates the number of hydrogen atoms. The formula (2n+2) means that for every carbon atom, there are two hydrogen atoms, plus two extra hydrogen atoms.

Examples:

* Methane (CH₄): n = 1 (one carbon atom), so the formula is C₁H_(2*1)+2 = CH₄.

* Ethane (C₂H₆): n = 2 (two carbon atoms), so the formula is C₂H_(2*2)+2 = C₂H₆.

* Propane (C₃H₈): n = 3 (three carbon atoms), so the formula is C₃H_(2*3)+2 = C₃H₈.

This formula helps you predict the molecular formula of any alkane based on the number of carbon atoms it has.