There are 20 memory registers, and they are independent of the 'stack'
and 'history list' registers. 10 registers are shown at a time,
and you can use the up/down button to toggle to the other set of 10
buttons.
To recall a value, simply tap any of the buttons to copy the memory
value to the display.
To store a value, simply tap any of the buttons to copy the display
value to the memory register. Optionally, you can select a
math operator from the bottom of the form, and when you subsequently
tap on one of the memory register buttons, the stored value will be
recalculated based on the displayed value and the operator. For
instance, in the displayed case above, tapping the '/' button, then
register button 2, would divide the current value (45) by the displayed
value (3) putting the result, 15, into the memory location.