Math...

[Ether]

The purpose of computing is insight, not numbers

-- Richard Hamming

whip up a simple simulation, crunch a few billion numerical integration floating-point calculations in a matter of seconds, and instantly plot a time-graph of the results (in color!),

create a spreadsheet and play with the inputs to see how they affect the outputs,

instantly plot a complex non-linear equation to visualize its behavior and help find its roots,

do a monte-carlo simulation of a probability or statistics problem,

fit a model to a set of experimental data,

etc etc etc

Using calculators, and especially personal computers, opens up worlds of understanding for those who will use these tools to gain insight, and not as a substitute for thinking.