Mathematics lets you take some vague ideas like less or more And make them more precise, like 7 or 3.14. Suppose Jill has three marbles and you go take away two. She'll have just one (unless she grabs the others back from you.) And that's just why such models may not yield the right amount: They fail to take human behavior fully in account. Math deals well with abstractions that conform to certain laws, But human beings are not so easily modeled with our flaws. These models often are employed in problems quite substantial, Like weather forecasts, bridge designs, or transactions financial. We often use the model to predict the real event, Which frequently will leave us wondering where the money went. It's not that math is inexact, or that it's incomplete. The model may be too abstract, when life is so concrete.