Bc

bc, for basic calculator (often referred to as bench calculator), is “an arbitrary-precision calculator language” with syntax similar to the C programming language. bc is typically used as either a mathematical scripting language or as an interactive mathematical shell.

A typical interactive usage is typing the command bc on a Unix command prompt and entering a mathematical expression, such as (1 + 3) * 2, whereupon 8 will be output. While bc can work with arbitrary precision, it actually defaults to zero digits after the decimal point, so the expression 2/3 yields 0. This can surprise new bc users unaware of this fact. The -l option to bc sets the default scale (digits after the decimal point) to 20 and adds several additional mathematical functions to the language.