Casio fx-991ZA PLUS II User Manual page 95

press after the argument to close the parentheses may cause
unwanted values or expressions to be included as part of the argument.
Example: (sin 30) + 15 (Angle Unit: Deg)
Older (S-V.P.A.M.) Model:
Natural Textbook Display Model:
(LineIO)
Failure to press
45.
here as shown below will result in calculation of sin
94
30 15
30 15
30 15 0,7071067812
15,5
15,5