Much depends on how precise I need for a given task.

My father was a carpenter. He could figure out layouts to the 1/16 of an inch or better. Did it all in his head.

Taking a road trip, I don't need to know to the exact penny or ounce how much fuel I used. Pulling a boat or trailer, I need to be more precise in planning mileage and stops.

Had a great 7th grade math teacher who was excellent at teaching practical math. Moving the decimal point when figuring 10% was an early lesson in tipping.

For even when we were with you, we gave you this rule: "If a man will not work, he shall not eat."

2 Thessalonians 3:10