# HP -28S Manual Page 76

For other functions, the symbolic constant
' I T
produces an expression
containing
'IT.
If you force a real-number result, the calculator uses the
12-digit approximation.
To demonstrate the difference between 3.14159265359 and
'IT,
calcu-
late the sine of each.
Put
I
' I T
I
in level 1 .
• GJ
I
ENTER!
Although this object looks like a name, it's actually an expression
with a single term, the symbolic constant
1r.
Force a real-number result using .... NUM
(to number)
. 1
+NUM!
3:
2:
1:
3.14159265359
BmlmmaallIDllllDmmJ
The 12-digit approximation to
7r
(3.14159265359) is returned to level
1.
Calculate the sine of the approximation to
7r.
SIN
3:
2:
1:
-2. 06761537357E-13
BmlmmaallIDllllDmmJ
The result (-2.06761537357 x 10-
13 )
isn't exactly 0 because the ar-
gument (3.14159265359) isn't exactly
7r.
Now calculate the sine of
7r.
3:
2:
-2.06761537357E-13
1:
0
BmlmmaamalllDmmJ
The SIN function recognizes the symbolic constant
7r
and returns the
exact result (0).
5: Real-Number Functions
75
I