Choosing the number base
Each base key converts the number on the display and switches to that base. 
switches to binary, base two, and the display shows a small b. 
switches to pental, base five, shown as a P. 
switches to octal, base eight, shown as an o. 
switches to hexadecimal, base sixteen, shown as an H. And 
returns to normal decimal numbers, and the base mark disappears. Only whole numbers are used: a fraction part is dropped, and negative numbers appear as complements.