(Carried over from this thread, in response to jurongresident's
query)
The general checksum formula for bus plates is
known by most (if not all) bus enthusiasts, and it's already
listed on Wikipedia.
In short:
Remainder table:
(this is cyclical in modulo 19, i.e., 19=0, 20=1, 21=2, 38=0,
etc.)
(Alternatively: Reverse
Remainder list. Subtract the earlier remainder from 19 to
get this list.)
But for convenience sake, it will be easier if we just consider
the 5-4-3-2 rule, and start from SG 0000 for example.
"S" and "G" correspond to "0" and "7" in modulo 19 respectively.
Their sum of products is 28,
which equals 9 in modulo 19. We shall
disregard the 4-digit number first. SG 0000 would
give a checksum of M.
Likewise for SBS (B=2, S=0,
sum of products = 18); SMB (M=13, B=2, sum of products =
125 = 11 (mod 19)); TIB (I=9, B=2, sum of products =
89 = 13 (mod 19)).
Using the remainder table, we have SG 0000
M, SBS 0000
B, SMB 0000
K, TIB 0000
H.
Digitwise,
Examples:
SG 1083: Increase remainder notch by 5, 0, 24, 6; total increase
=35, modulo increase =16, equivalent to -3. Hence M <-- P <--
R <-- S.
SG 5025: Increase remainder notch by 25, 0, 6, 10; total
increase =41, modulo increase =3. Hence M --> L --> K -->
J.
SG 5016: Increase remainder notch by 25, 0, 3, 12; total
increase =40, modulo increase =2. Hence M --> L -->
K.
SBS 1: Increase remainder notch by 0, 0, 0, 2; total increase
=2, modulo increase =2. Hence B --> A -->
Z.
SBS 9889: Increase remainder notch by 45, 32, 24, 18; total
increase =119, modulo increase =5. Hence B --> A --> Z -->
Y --> X --> U.
SG = SBS-2000.
SBS3001D > SG1001D
SBS7300P > SG5300P
SBS3701S > SG1701S
