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(12C) Greatest Common Divisor
01-06-2018, 12:29 AM (This post was last modified: 01-07-2018 02:35 AM by Gamo.)
Post: #1
(12C) Greatest Common Divisor
Quick and Simple program to find GCD of two integers.

Code:

 -
LSTx
X<>Y
ENTER
 x
 √
X=0
GTO 10
GTO 01
X<>Y

Thanks to Dieter for the trick by make sure that Y is greater than X so ABS don't have to be use and here is the update program.

Code:

X≤Y
X<>Y
X<>Y
  -
LSTx
X<>Y
X=0
GTO 10
GTO 01
X<>Y

Example:
Test 1 GCD (256, 656) is 16 ---> 256 ENTER 656 R/S
Test 2 GCD (12345, 67890) is 15 ---> 12345 ENTER 67890 R/S

Remark: Test 2 will run faster on HP 12C+

Gamo
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01-06-2018, 01:10 AM
Post: #2
RE: (12C) Greatest Common Divisor
I love your programs Gamo since I use the HP-12C all the time! Thanks for the post.
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01-06-2018, 04:23 AM
Post: #3
RE: (12C) Greatest Common Divisor
Thank You Carsen

Gamo
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10-08-2021, 08:08 AM (This post was last modified: 10-08-2021 08:15 AM by Gamo.)
Post: #4
RE: (12C) Greatest Common Divisor
Long time no update for the GCD program.

I dig around some HP manual and found the HP-91 User's Manual on

Page 122 demostrated the manually keys in steps to find GCD with this

algorithm the slower computation speed on Original Classic HP-12C

will do really well and here I adapted this to run on the HP-12C

Code:

01 STO 1
02 R/S
03 ENTER
04 ENTER
05 RCL 1
06 ÷
07 INTG
08 RCL 1
09  x
10  -
11 X=0
12 GTO 19
13 RCL 1
14 X<>Y
15 STO 1
16 CLx
17  +
18  GTO 03
19  RCL 1
20 GTO 00

Example:
GCD (153, 351)

153 [R/S] display 153
351 [R/S] display answer 9

GCD = 9

Gamo 10/2021
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