I still have a K&E log/log deci-trig slide rule in a nice leather case. I do not use it of course. What the hell I have probably forgotten how to use it. My Casio fx300 calculator cost $12. It can do things unheard of at the time I bought the slide rule. My more advanced Casio fx9600GII can do matrix math, spread sheets, conics, statistics, graph equations and find precise locations on the curves, and some other stuff that I do not even know how to do. Yikes, it is so much smarter than me that I am truly humbled.

The world has passed me by. It has been an interesting, sometimes fun, ride however.

Billy, assure your sons that calculus has many practical uses. Calculate instantaneous piston velocity for example. Calculate the dimensions of a a box that uses the least amount of material to hold a given volume of ingredients..and much much more.... Trig is essential for many crafts. A roofer uses trig, as do carpenters, plumbers, and quilt makers too. Either of these courses of instruction is worth studying if for no other purpose than to expand the borders of ones mind.