Demos Graphing Calculator is a good mobile substitute ... Some of its features include trig functions, result history, percentage support, unit conversions, multi-window support, and more.

Scientific calculators were invaluable to most of us through high school and college, freeing us from the yoke of using tables to calculate logarithms and trigonometric functions. Once out in the ...

everyone in class had a TI graphing calculator. In some ways this was better than a cell phone: If you wanted to play BlockDude instead of doing trig identities, this was much more discrete.