I’m about to get a PhD in math, and I am not the best at mental arithmetic either. I used to be really bad, but teaching has forced me to improve by a lot. It was very annoying for me to go back and forth between my notes/computer and the blackboard whenever there was a big multiplication, so I just slowly got better at doing it in my head. Also, it had the added benefit of letting me improvise more.
My college roommate got insanely good at it when he set an alarm on his phone that required him to do some calculation before he could turn it off. After about one semester, he was doing those half asleep lol. I think he finally decided on an alarm that would need him to walk outside and scan a QR code to turn off.
Another method to get good at mental arithmetic: At the supermarket checkout, pay in cash—and do your best to minimize the number of coins you end up with. Start calculating right after you’ve put your groceries on the checkout conveyor belt: Pour all your coins in your hand and then calculate in advance which coin combination you would give for which grand total that might result (or just for the decimal places thereof).
I’m about to get a PhD in math, and I am not the best at mental arithmetic either. I used to be really bad, but teaching has forced me to improve by a lot. It was very annoying for me to go back and forth between my notes/computer and the blackboard whenever there was a big multiplication, so I just slowly got better at doing it in my head. Also, it had the added benefit of letting me improvise more.
My college roommate got insanely good at it when he set an alarm on his phone that required him to do some calculation before he could turn it off. After about one semester, he was doing those half asleep lol. I think he finally decided on an alarm that would need him to walk outside and scan a QR code to turn off.
Another method to get good at mental arithmetic: At the supermarket checkout, pay in cash—and do your best to minimize the number of coins you end up with. Start calculating right after you’ve put your groceries on the checkout conveyor belt: Pour all your coins in your hand and then calculate in advance which coin combination you would give for which grand total that might result (or just for the decimal places thereof).