# Why do we multiply molar concentrations and not sum them, and why there's no squared sign here?

## From Wikipedia's page Antigen-Antibody Interaction Why do we multiply [Ab] and [Ag] and not, say, sum them up? Why the final term has no squared signs? We've basically multiplied two similar terms.

${A}_{b} + {A}_{g} r i g h t \le f t h a r p \infty n s {A}_{b} A g$
where ${A}_{b} \mathmr{and} {A}_{g}$ are two different species interacting in 1:1 mole ratio. So the multiplication of their concentration terms raised with unit power does not result the squaring.
Again $\left({A}_{b} {A}_{g}\right)$ being associated single species with unit stoichiometric coefficient squaring does not arise.