The only equations and formulas most people use daily are ones that involve totaling amounts, adding tax or shipping costs, or determining discounts or tips.

Some professionals in investments, insurance, science, medicine, architecture, construction, or engineering make use of formulas and equations more complicated than that. Some compute rates of return, compound interest, expected loss rates or amounts. Some compute areas, volumes, lengths. Others compute mixtures and doses. Some compute the effects of forces or flows or heat. Many professions have developed "rules of thumb," calculating tools, tables, or shortcut calculations so that the use of complicated formulas is avoided.

Some professionals in investments, insurance, science, medicine, architecture, construction, or engineering make use of formulas and equations more complicated than that. Some compute rates of return, compound interest, expected loss rates or amounts. Some compute areas, volumes, lengths. Others compute mixtures and doses. Some compute the effects of forces or flows or heat. Many professions have developed "rules of thumb," calculating tools, tables, or shortcut calculations so that the use of complicated formulas is avoided.