Divide - Make Button1 the default
Multiply - Make Button2 the default
Subtract - Make Button3 the default
Seven - Move the pointer up and left
Eight - Move the pointer up
Nine - Move the pointer up and right
Add - Double-click the default button
Four - Move the pointer left
Five - Emulate the default button
Six - Move the pointer right
One - Move the pointer down and left
Two - Move the pointer down
Three - Move the pointer down and right
Zero - Lock the default button down
Decimal - Release the default button, if locked