HP 30b Business Professional Calculator - Manual (Page 33)

Mathematical Calculations 25
Recalling a Menu Item Value in a Menu
In a menu, you can recall the current value of a menu item. For example, open the Interest
Conversion menu (IConv) by pressing
:&
. With Nom.% displayed, pressing
2*L==
calculates 2 times the nominal rate. This feature is useful when
you need to insert the contents of a menu item into an algebraic operation.
Recalling and Storing Values in the Data and Cash Flow Menus
If you store an index (i) from 0 to 99 in the variable 0, you can then use the store/recall
features to store a number in the Data and Cash Flow menus. Press either
:$
or
L
,
followed by the CashFlow key
C
, to either store or recall a number, as desired, in the
CF(i/2) (if i is even) or #CF((i-1)/2) if i is odd.
In addition, you can store or recall x(i/2+1) if i is even, or y((i+1)/2) if i is odd, as desired,
by pressing the Data key
:y
instead of the CashFlow key,
C
, as shown above.
Rounding Numbers
All calculations are performed internally with 15-digit precision and are rounded to 12 digits
when returning the results. In certain instances, calculations are performed internally with
greater than 15-digit precision.
When displayed, a number is further rounded to the number of digits after the decimal point
set by the FIX item in the Mode menu. The default setting is two digits to the right of the
decimal point. For more information, refer to the section titled, The Mode Menu: Setting
Preferences in Chapter 1.
NOTE: the FIX setting only affects the display; it does not affect the actual numbers.
Percentages
In Algebraic or Chain modes, pressing
%
divides a number by 100. For example, pressing
25%
returns 0.25.
To find a percentage of a given number, key in the number and multiply it by the desired
percentage, followed by
=
. For example, to find 25% of 200, press
200*25%=
to return a result of 50.
To add or subtract a percentage of a number, key in the first number, followed by
+
or
-
and the percentage followed by
%
. Finish your calculation with
=
. For example,
to add 10% to 50, press
50+10%=
to return a result of 55.