As a math teacher, my suggestion to the students is during practice to try to do calculations without a calculator to invoke a bit of number sense so when they use calculators be able to notice in the result if they did a wrong input. It happens to input “14” instead of “41” . I feel like able to do mental arithmetic with double digit numbers can be helpful
In hindsight, I do think the right approach is not to use calculators till secondary school (about 14~15 years of age). Having a feel for numbers and how they should behave under addition/multiplication/exponentiation and ability to mentally do two digit calculations as you said is critical, and should be an “automatic” capability
As a math teacher, my suggestion to the students is during practice to try to do calculations without a calculator to invoke a bit of number sense so when they use calculators be able to notice in the result if they did a wrong input. It happens to input “14” instead of “41” . I feel like able to do mental arithmetic with double digit numbers can be helpful
In hindsight, I do think the right approach is not to use calculators till secondary school (about 14~15 years of age). Having a feel for numbers and how they should behave under addition/multiplication/exponentiation and ability to mentally do two digit calculations as you said is critical, and should be an “automatic” capability