Pro tip: I counted on my fingers until age 23 and the moment I found out was a 3am gas station receipt
I was at a Speedway off I-75 in Ohio buying a $4.87 coffee and a Slim Jim, and the total came to $6.12. I stood there doing the 8 plus 4, carry the 1 thing in my head, and the cashier just said "six twelve" before I finished. That night I added up my rent, phone, and car insurance for April by counting on my knuckles, and half my budget was off by almost $90. Now here is the fight I want to have. My roommate thinks finger counting is fine and schools ruined us by banning it, so the answer is to ditch mental math and just use your phone. My uncle thinks if you never learn to do it in your head you get ripped off at flea markets and car lots. So which is it, is finger counting a real skill you should keep, or is it a crutch I should have dropped way earlier?
Your uncle's flea market point only works if the seller is honest, and the shady ones know you're not adding it up either way. The $90 miss on your budget wasn't the fingers, it was checking once at 3am instead of writing it down as you went.