[jude24]

I wish I had taken the time to learn this.

I've gotten lazy -- I don't like to do simple arithmatic without a calculator.

If pressed, I could do most arithmatic with a pencil and paper. Give me trig tables, and I could do that too. But a calculator is so much quicker, and less likely to make a mistake (and a scientific calc is what? $10?)

[Diddley]

. . . But a calculator is so much quicker, and less likely to make a mistake

You are right.
A person "needs" to learn how to "do" math, so that he/she can decide what procedure to use and to evaluate answers for reasonableness.
However - as one who has used math for 6 decades - I now find that I "depend" on a calculator.