checkdigit calculation for HP-17b

[Thomas Klemm]

(07-28-2015 06:48 PM)Gerson W. Barbosa Wrote:  
C=10*MOD(MOD(0*L(T:0)+L(S:Σ(I:1:9:1:0*L(T:G(T)+I*MOD(N:10))+(10-I)*MOD(N:10)
+0*L(N:IDIV(N:10)))):11):10)+MOD(MOD(G(T)+9*IDIV((MOD(G(S):11)):10):11):10)

If you add both s and t you will get \(10\times\sum\) of the digits which is just: \(-\sum\) of the digits mod 11. If you call that u then s can be calculated as \(s=u-t=-(-u+t)\).
This might be easier to implement.

Just an idea \(\cdots\)
Thomas