Using the Psion desk and scientific calculator.
The Psion calculator can be viewed as a simple desk calculator, or as a scientific calculator. You can use the keyboard or the stylus to operate it. You can flip the layout to suit right on left handed users. Operations in one view do not alter the other view, so you can swap between them without disturbing results. In the Series 7, you can use the embedded numeric keypad as well as the regular keyboard numerals.
A simple four function plus percentage key calculator with a single memory and memory add and memory subtract buttons. It provides a visual scrolling tape roll of past calculations.
A 26 memory scientific calculator with normal notation, fixed number of digits after the decimal point, and scientific notation. You can edit and reuse the last ten expressions entered, and insert the last answer at any point in the calculation. Trig functions include sine, cosign, tangent, hyperbolic trig functions sinh, cosh, tanh, and the inverse arcSine, arcCosine, and arcTangent. Powers, roots, reciprocals, common logorithms and natural logs, factorials, about 24 functions keys including the inverse function.
Base conversions. Explain use.
Shift+Ctrl+I lists keyboard shortcuts, which are different for each model of the calculator.
Ip and down arrows scroll through the till roll, or the last ten calculations in scientific view. M changes the sign of a number.
Steven Pemberton notes a hint about calculator for the Revo: typing just y, u, i, o, p is all that is necessary for the arithmetical functions (i.e. you don't have to press fn+i to get +, just i is enough).
You do need to note that different models of the Psion appear to have different keyboard shortcuts. Check your own model carefully.