@puddleglum1066, and the abacus does addition and subtraction faster and more accurately than calculators. Entering the digits reveals the answer: no + or Enter key to press. I still use a Chinese abacus (which has 2 beads on top and 5 on the bottom of each column traditionally used for bookkeeping on multiplication and division) to add and subtract hexadecimal when doing low level debugging on the computer.
As soon as you need to do sales tax (which can be looked up in a table for retail, however), discounts, or other multiplication, a modern calculator becomes much more attractive.
@puddleglum1066, and the abacus does addition and subtraction faster and more accurately than calculators. Entering the digits reveals the answer: no + or Enter key to press. I still use a Chinese abacus (which has 2 beads on top and 5 on the bottom of each column traditionally used for bookkeeping on multiplication and division) to add and subtract hexadecimal when doing low level debugging on the computer.
As soon as you need to do sales tax (which can be looked up in a table for retail, however), discounts, or other multiplication, a modern calculator becomes much more attractive.