HP 15C: Prime Factorization
This program does exactly this: factors an integer. Fix 0 mode is activated during
execution. Each factor is displayed by
pressing [R/S]. The calculator is
returned to Fix 4 mode when the program is completed. If the integer is a prime number, the program
just returns the integer entered.
|
Step
|
Key
|
Code
|
|
001
|
LBL B
|
42, 21, 22
|
|
002
|
FIX 0
|
42, 7, 0
|
|
003
|
STO 2
|
44, 2
|
|
004
|
STO 0
|
44, 0
|
|
005
|
2
|
2
|
|
006
|
STO 1
|
44, 1
|
|
007
|
LBL 3
|
42, 21, 3
|
|
008
|
RCL 0
|
45, 0
|
|
009
|
RCL÷ 1
|
45, 10, 1
|
|
010
|
ENTER
|
36
|
|
011
|
FRAC
|
42, 44
|
|
012
|
X=0
|
43, 20
|
|
013
|
GTO 2
|
22, 2
|
|
014
|
1
|
1
|
|
015
|
STO+ 1
|
44, 40, 1
|
|
016
|
GTO 3
|
22, 3
|
|
017
|
LBL 2
|
42, 21, 2
|
|
018
|
RCL 1
|
45, 1
|
|
019
|
R/S
|
31
|
|
020
|
R↓
|
33
|
|
021
|
R↓
|
33
|
|
022
|
STO 0
|
44, 0
|
|
023
|
1
|
1
|
|
024
|
-
|
30
|
|
025
|
X≠0
|
43, 30, 0 (TEST 0)
|
|
026
|
GTO 3
|
22, 3
|
|
027*
|
RCL 2
|
45, 2
|
|
028
|
FIX 4
|
42, 7, 4
|
|
029
|
RTN
|
43, 32
|
Example: 150. Factors:
2, 3, 5, 5 (when the display reads 150.0000 the factorization ends)
* Thanks to Ross Barnes to pointing the typo to me. The key is now correct. - Eddie 11/13/2021
This blog is property of Edward Shore, 2017.