HP 42S - Manual (Page 7)

1.41421356237
As you can see the numbers are not truncated but rounded.
Not all numbers can be seem with a fixed decimal precision. If you put 4 digits for fixed precision
the number π will appear as 3.1416 but if one calculate 10
8 (do this by doing 8 ▀ 10 x ) what
you are going to see is 100,000,000.000 with 3 decimal digits. This happens because the calculator
cannot show more than 12 digits at a same line.
2.6.2 The ALL function
We already talked about ALL function. It makes the calculator to show all of its precision.
2.6.3 The SCI function
The SCI function works just like FIX one but puts the calculator in “scientific” mode. The numbers
will be shown as a decimal number between 0 and 1 times a power of 10.
For example 1000 will be represented as 1.00E3 with you put the calculator in scientific mode with
2 digits. 1.00E3 means 1.00x 10
3 . The π number will appear as 3.14E0.
Actually even when in FIX mode the calculator will turn in scientific notation to give some answers.
For example if you calculate 1.0001-1 with FIX 3 you are not going to get 0.000 but 1.000E-4. This
means that the calculator is “smart” and show the result in the best way as possible.
Exercise. Show that 1.0001-1 gives 1.000E-4 in FIX 3 mode.
Answer:
First we put the calculator in FIX 3 mode by doing ▀ DISP FIX 0 3.
Then we do 1 . 0 0 0 1 ENTER 1 – and we get the answer.
As you can see when you are in FIX mode a sign ■ appears on the right side of FIX name in the
DISP menu. This means FIX mode is active. The same happens with SCI, ALL, etc.
It is out of our scope to give a full description of scientific notation. In case of need please report to
a first book of physics for high school or college.
2.6.4 The ENG function
The ENG function puts the calculator in engineering notation. It looks like scientific notation but
now the first number does not need to be between 0 and 1 but can be between 0 and 1000 and the
power will be always 3 manifold.
Example: 100 will be represented by 100.E0 in ENG 2 mode while 1000 will be 1.00E3 in the same
mode. Why do we get 100.E0 for 100 instead of 100.00E2 in ENG 2 mode? Because the calculator
shows in engineering mode the same number of digits it shows in scientific mode.
2.6.5 RDX. And RDX, functions
In some countries like Brazil we use ',' for decimal point instead of '.' and also '.' instead of ',' for
1,000 and 1,000,000 etc.
For example π is written here (Brazil) as 3,141 etc and not as 3.141 etc. In FIX 3 mode one million
is written here as 1.000.000,000 and not as 1,000,000.000 as in English use. By pressing RDX, you