Section 2
Display Control
The HP-41C provides many display capabilities for both numbers and ALPHA characters. You can control the format of how all numbers are seen in the display. But regardless of the display options in effect, the HP-41C always represents each number internally as a 10-digit mantissa and a 2-digit exponent of 10. Thus when the calculator is set to display only four digits past the decimal point, the fixed constant pi, which is always represented internally as 3.141592654 × 1000, will appear in the display as 3.1416.
For example, when you compute 2π, you might see the answer to only four decimal places:
Keystrokes Display    
2 g    ×   6.2832    
However, inside the calculator all numbers have 10-digit mantissa and 2-digit exponents of 10. So the calculator actually calculates using full 10-digit numbers.
2.000000000 × 1000 g   3.141592654 × 1000  × 
yields an answer that is actually carried to full 10 digits internally:
  6.283185308 × 1000  
You see only these digits...  
 ...but these digits are also present internally.
Display Format Control
There are three functions, FIX , SCI , and ENG , that allow you to control the manner in which numbers appear in the HP-41C display.
FIX displays numbers in fixed decimal point format, while SCI permits you to view numbers in scientific notation format. ENG displays numbers in engineering notation, with exponents of 10 shown in multiples of three (e.g., 103, 10–6, 1012). By pressing a digit key (0 through 9) after any of these display control functions, you specify the number of decimal digits displayed. The HP-41C will actually prompt you with an _ (underscore) for the number (0 through 9) when you press the display format function.
No matter which format or how many digits you choose, the display control alters only the