Emacs provides a method for working out numbers in two’s complement form `M-x calc` Turn on calc mode `O d2` Turns on two's complement binary `b w 8` Sets the word length to 8 bits `d z` Displays leading zeroes Now you can enter numbers. Don’t forget to use underscore for negative numbers `_3 (-3) gives 2##11111101` You can press `y` to yank the result back into the last buffer. ## Quick Conversions if you want to quickly convert between binary, denary and hex you can use quick calc mode: To convert 17 from Denary to Binary `C-x * q ` Enter quick calc mode `17` Hit enter ``` Result: 17 => 17 (16#11, 8#21, 2#10001, " ") ``` To convert 1100 from Binary to Denary (or Hex) `C-x * q` Enter quick calc mode `2#1100` Enter in minibuffer. Use `16#` to enter a Hex number ``` Result: 12 => 12 (16#C, 8#14, 2#1100, " ") ``` ## See Also - [[Calc Mode 0 Basics]] - [[Calc Mode 1 Binary Numbers]]