As with other CALC 1 calculators, press and hold any key for a hint.
The "f()" displays the list of CALC 1 functions.
The "ans" key inserts a variable into the formula that contains the last answer.
When an operator is the first entry of a formula, "ans" is inserted in front of the operator. So when you start a formula by tapping "/1.5", the formula is "ans/1.5". If you need to start a formula with a negative number, tap "shift (-)" to insert a negative sign.
Repeated tapping of the "=" for formulas with "ans" (ans + 1, for example) will re-evaluate the formula with the updated value for "ans". If you need to start with a "-", tap shift (-) for a minus sign that will not insert "ans".
The arrow keys will display previous formulas.
In landscape, there is a toolbar for access to the History List, List Manager and Options.