HP 48G - Arithmetic and Postfix Notation

ARITHMETIC AND PosTFix NOTATION
“Crunching” Numbers on the Stack
Every good calculator should do arithmetic quickly
and easily. HP calculators pioneered a very efficient
style of operation called postfix notation (a general-
ized version of the method known as “RPN”"), in which
you put the arguments on a stack first, then perform
the operation last. This precludes the need to use
parentheses—any intermediate results simply “float”
in the stack until needed. Here are some examples:
Add 26 + 82:
Subtract 86 - 32: 6]ENTER)(3)2)(—]
For a negative number, use (+/-): (2]+/=JENTER).
Multiply 62 x 45:
Divide 85 + 20: (8]5ENTER)(2]0)(=)
Raise 42 to the 5th power:
Take V20:
Square 25: (2]5)(e[x?)
Find the reciprocal of 85: (8]5)(V/x]
Calculate (5+2)*: (5]ENTER)(2)(+)(3)(Y¥
Calculate 5 + 2%
Calculate 6\10: (6ENTER)(1)0)(x)(X)
Calculate (21+7)**: 1]JENTER)(7)(+)(4 [ENTER)(5) =)
Find sin(25): (2]5]SIN)
Find arctan(1): (1){&JATAN
Find log(2) (common log—base 10):
Find In(3) (natural log—base e): (3)[>]LN
Find e': (1)o](q)e¥
Postfix Notation—Everywhere in the Machine
Again, note the postfix notation method in the above
calculations: Arguments first, operation last. And
note also that the arguments are consumed by the
operation. For example, after adding £& and 3, you
getonly the result (1HZ) on the stack; the arguments,
£t and B2 are gone. This is true in general for oper-
ations throughout the calculator (whether or not you
expectany stack results): If an operation uses any ar-
guments, you put them on the stack prior to executing
the operation. The arguments are then consumed
(regardless of results). For example, to set the dis-
play to 2 decimal places, you use the F I command,
with asthe argument: JENTER) )] F | X« ENTER).
The argument is consumed (and, in this case, no new
result objects appear on the stack).
Arithmetic and Postfix Notation 5