If I need more than 2 decimals of precision, I’d use the calculator. But by the time I type it in I already know to expect an answer of about 0.23. If the calculator give me anything else, I’ll redo it more carefully.
A good student knows enough basic math to know whether or not their calculator did what they thought it did, or if they mistyped something, had it in the wrong mode, missed order of operations, etc.
Gonna be honest my guy I don’t believe you did 4/17~=0.23 in your head. And if you did, great for you but, most people can’t do that.
I did, and you can too. Here’s how: 4/17 is about 4/16 = 1/4 = 0.25, but a little less because 1/16 is greater than 1/17. The error term is about 4/(16^2) or 4/250, so subtract about another 2 hundredths to 0.23.
