HP 15c - Manual (Page 115)

Section 10: The Index Register and Loop Control 115
To display fixed point notation for all possible decimal places on the
HP-15C:
Keystrokes Display
| ¥
Run mode.
´ B 9.000000000
8.00000000
7.0000000
6.000000
5.00000
4.0000
3.000
2.00
1.0
0.
Display at ´©instruction.
0.
Display when program halts.
Further Information
Index Register Contents
Any value stored in the Index register can be referenced in three different
ways:

Using V like any other storage register. The value in R
I
can be
manipulated as it is: stored, recalled, exchanged, added to, etc.

Using V as a control number. The absolute value of the integer
portion in R
I
is a separate entity from the fractional portion. For indirect
branching, flag control, and display format control with V, only this
portion is used. For loop control, the fractional portion is also used, but
separately from the integer portion.
*

Using % as a reference to the contents of another storage register.
The % key uses the indirect addressing system shown in the tables on
pages 107 and 108. (In turn, the contents of that second register may be
used as a loop control number, in the fashion described above.)
*
This is also true for the value in any storage register used for indirect loop control.