HP 35s HP 35s scientific calculator - User Guide - Page 116

To change the number, type the new number and press . This new number writes over the old value in the X-register. You can enter a number as a fraction if you want. If you need to calculate a number, use normal keyboard calculations, then press . For example, you can press 2  5  in RPN mode, or press 2 5 in ALG mode. Before pressing , the expression will display in line 2, and after pressing , the result of the expression will display in line 2. To cancel the prompt, press . The current value for the variable remains in the X-register and displays in right-side of the line two. If you press  during digit entry, it clears the number to zero. Press  again to cancel the prompt. To display digits hidden by the prompt, press  . In RPN mode,each prompt puts the variable value in the X-register and disables stack lift. If you type a number at the prompt, it replaces the value in the X-register. When you press , stack lift is enabled, so the value is saved on the stack. The Syntax of Equations Equations follow certain conventions that determine how they're evaluated: How operators interact. What functions are valid in equations. How equations are checked for syntax errors. Operator Precedence Operators in an equation are processed in a certain order that makes the evaluation logical and predictable: 6-14 Entering and Evaluating Equations