Post Reply 
12c program how many factors does a number have
12-06-2018, 08:32 PM
Post: #1
12c program how many factors does a number have
Haven't you ever wondered how many factors a certain number has? If you have, would you like a quick way to find out on the HP-12c?

Code:

Reg 0 = input #
Reg 1 = factor count
Reg 2 = square root of input #
Reg 3 = trial factor

Enter the number you are curious about and press R/S.  On the newer 12c+, it will give you the answer very quickly; on the older ones, a bit longer.

The RPN program is only 28 lines long (a perfect number, by the way).

01 STO 0
02 SQRT X
03 STO 2
04 FRAC
05 X=0
06 GOTO 09
07 2
08 GOTO 10
09 1
10 STO 1
11 2
12 STO 3
13 RCL 0
14 X<-->Y
15 /
16 FRAC
17 X=0
18 GOTO 20
19 GOTO 22
20 2
21 STO+1
22 1
23 STO+3
24 RCL 2
25 RCL 3
26 X<=Y
27 GOTO 13
28 RCL 1

I once learned a quick way to determine the number of factors a number has using pencil and paper. Do the prime factorization of the number. Then, add 1 to the exponent of each prime factor and multiply these numbers together. The answer is the number of factors that the number has.
Find all posts by this user
Quote this message in a reply
Post Reply 




User(s) browsing this thread: 1 Guest(s)