dc — stdin stdout  file  opt help version
dc [options
] [files
]
The dc
(desk calculator)
command is a reversepolish notation (RPN), stackbased calculator
that reads expressions from standard input and writes results to
standard output. If you know how to use a HewlettPackard RPN
calculator, dc
is pretty easy to
use once you understand its syntax. But if you’re used to
traditional calculators, dc
may
seem inscrutable. We’ll cover only some basic commands.
For stack and calculator operations:

Quit 

Print the entire stack. 

Delete (clear) the entire stack. 

Print the topmost value on the stack. 

Pop (remove) the topmost value from the stack. 

Set precision of
future operations to be 
To pop the top two values from the stack, perform a requested operation, and push the result:

Addition. 

Subtraction. 

Multiplication. 

Division. 

Remainder. 

Exponentiation (secondtotop value is the base, top value is the exponent). 
To pop the top value from the stack, perform a requested operation, and push the result:

Square root. 
Examples:
$ dc4 5 + p
Print the sum of 4 and 5 92 3 ^ p
Raise 2 to the 3rd power and print the result 810 * p
Multiply the stack top by 10 and print the result 80f
Print the stack 80 9+p
Pop the top two stack values and print their sum 89
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