Online Scientific Calculator. For help refer to the Instruction manual and to the Online Scientific Calculator blog entries. This is a formula calculator. Enter your expressions in the same order as you would write them on paper. Then press '=' to display the result. Use parenthesis to alter the order of operations or to specify function ... On a Reverse Polish Notation calculator, the "Enter" function would do the same. Using a common operator (plus, minus, multiply, or divide) will make the operator act from the first stack to the second stack. For example, the Reverse Polish Notation "12 3 /" means "take the numbers 12 and 3, then divide 12 by 3". According to the standard notation for inverse functions (f-1), you will also often see these written as sin-1, cos-1, tan-1 csc-1, sec-1, and cot-1. Beware: There is another common notation that writes the square of the trig functions, such as (sin(x)) 2 as sin 2 (x).