Casio fx-100AU PLUS User Manual page 36

k When I execute a function calculation, why do I get a calculation result
that is completely different from older CASIO calculator models?
With a Natural Textbook Display model, the argument of a function that
uses parentheses must be followed by a closing parenthesis. Failing to
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 v
Older (S-VPAM) Model:
Natural Textbook Display Model: b s 30 )+ 15 =
Failure to press ) here as shown below will result in calculation of sin 45.
s 30 + 15 =
E-35
s 30 + 15 =
0.7071067812
15.5
15.5