Here are LCM and GCD routines for the 32SII/33S that I came up with. Note that LCM(m,n)= m x n / GCD(m,n) and LCM is computed here using Euclid's method. It's really fast, worst case is on the order of log base 2 of the smaller of m, n.

LCM: call with m,n in x,y return with LCM in x

uses: A, B, x,y,z,t

L01 LBL L

L02 STO A

L03 x<>y

L04 STOx A

L05 XEQ G

L06 RCL A

L07 x<>y

L08 /

L09 RTN

GCD: call with m,n in x,y return with GCD in x

uses: B, x,y,z,t

G01 LBL G

G02 x>y?

G03 x<>y

G04 STO B

G05 0 | these 7 instructions are just

G06 ENTER | to compute y mod x. On a 33S

G07 CMPLX+ | You can replace these with

G08 / | the single instruction:

G09 IP | RMDR

G10 x |

G11 - |

G12 RCL B

G13 x<>y

G14 x>0?

G15 GTO G

G16 RCL B

G17 RTN