HP HP-67

Section 2
Display Control
In the HP-67, you can select many different rounding options for dis-
play of numbers. When you first turn on the HP-67, for example, the
calculator ‘‘wakes up’’ with numbers appearing rounded to two
decimal places. Thus, the fixed constant 7r, which is actually in the
calculator as 3.141592654, will appear in the display as 3.14 (unless
you tell the calculator to display the number rounded to a greater or
lesser number of decimal places).
Although a number is normally shown to only two decimal places, the
HP-67 always computes internally using each number as a 10-digit
mantissa and a two-digit exponent of 10. For example, when you
compute 2 X 3, you see the answer to only two decimal places:
Press Display
2D
3@
However, inside the calculator all numbers have 10-digit mantissas
and two-digit exponents of 10. So the HP-67 actually calculates using
full 10-digit numbers:
2.000000000 X 10% EGEGE 3.000000000 X 10°E3
yields an answer that is actually carried to full 10 digits internally:
6.000000000 x 10
——
You see only these digits..l
...but these digits are also present.
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