So far, the only one I’ve thought of is accountant. My father’s a CPA, and he finds it useful to be able to do quick calculations in his head when looking for errors.

It would be nice if cashiers were better at mental math. When you buy something that’s 77 cents, it would be nice if they could figure out why you might hand them $1.02. It seems they usually either ask “Why’d you give me two pennies?” or have to enter $1.02 into the cash register to compute the change.

Any field which involves measurement.

Accounting, engineering, medicine, carpentry, sociology, anthropology, finance, any management position, astronomy, physics, economics, architecture, just to name a few.

Securities traders need to be facile with numbers. Even though a lot of the calculations are computer generated now, a trader still needs to understand the algorithms and relative risk/reward.

It sounds a bit odd but I work at a pet store working with fish. Mental math is incredibly useful. Chemical dosing, tank sizes, filter sizes, flow rates, lights. pretty much everything depends on math in some way or another

I’ve heard that it’s helpful to astronauts if they can do some complex calculations in a short period of time.
Mental math would help a lot with that.

Twiddling your thumbs. Counting fishy’s in a pond.

Kidding, kidding. Sciences/physics a lot, accounting, number-crunchers, mathematics professors, etc. Economics.

@GeorgeGee: why would you give a cashier $1.02 for a $0.77 purchase?

In nursing and medicine it is useful to stop you killing your patients with the wrong doses of drugs.

@ratboy so that the cashier can give you a quarter as change.

@ratboy, so you get a quarter back as change instead of two dimes and three pennies.

All knowledge worker careers. During discussions you need ad-hoc mental math and if people ever used a calculator for simple mental math it’d be totally embarrassing. Example: During a meeting your boss says, suppose we increase this by 10% when all of our 80 machines produce 60 units per hour… and so forth. For everyone in the room this should not take longer than a second.

Is this a serious question? I can’t think of a single career for which mental math is not useful.

It’s like asking if there are any careers that involve the ability to think quickly and respond intelligently with language. Can you think of any careers where that skill would be useful? Well, the same career would benefit from an ability to do quick calculations in one’s head.

Commercial maintenance. I’ve had to figure out the proper size of a heater controller (amperage rating) to use or make by measuring the ohm’s on the heating elements inside of molds for mold injection units. That’s just one small example but I have to use math alot in my head for many situations especially relating to Ohm’s Law.