HP 15c - Manual (Page 175)

Appendix: Accuracy of Numerical Calculations 175
Subroutine "B" below, which uses such a trick,* is a very short program that guarantees nine
correct significant digits on a 10-digit calculator. It uses labels "B", ".7", and ".8" and
registers R
0
through R
9
and the Index register. To use it, key in c v b v a, run
subroutine "B", and wait for results as before.
Keystrokes Display
|¥
´CLEARM 000-
´bB 001-42,21,12
OV 002- 44 25
) 003- 33
O0 004- 44 0
O8 005- 44 8
® 006- 34
O1 007- 44 1
O9 008- 44 9
´i2 009-42, 8, 2
´b.8 010-42,21,.8
´CLEAR∑ 011- 42 32
l8 012- 45 8
O7 013- 44 7
l÷V 014-45,10,25
|& 015- 43 34
lV 016- 45 25
|w 017- 43 49
l9 018- 45 9
´X7 019-42, 4, 7
® 020- 34
l8 021- 45 8
|w 022- 43 49
) 023- 33
|w 024- 43 49
l7 025- 45 7
|a 026- 43 16
l9 027- 45 9
|a 028- 43 16
|£ 029- 43 10
tB 030- 22 12
v 031- 36
*
Program "B" exploits a tricky property of the z and z keys whereby certain calculations can be carried out to 13 significant digits before being rounded
back to 10.