Wednesday, March 22, 2017

HP 15C: Prime Factorization

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.

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