> If you need to get detailed, or your estimates don't line up with what your savings account is actually doing I think the point is that the ability to count

> If you need to get detailed, or your estimates don't line up with what your savings account is actually doing I think the point is that the ability to count pennies when called upon is part of what keeps your rough intuitions properly calibrated. If one literally cannot do exact arithmetic when necessary (whether mentally, manually, or with a calculator), then how does the gut learn what to pay attention to, and when it might be wrong?