This is where algebra comes in: chose a two-digit number equates to (10 x a) + b. Then substract the sum of the digits. This results in ((10 x a) +b)) - (a+b) which simplifies to (10 x a - a) + (b-b) or 9 x a. Provided the symbol repeats every 9 places, the same symbol will come up no matter what number you chose. The trick is, they change the symbol on the multiple of 9. Whatever the order, the same symbol is on 9,18, 27, etc.
Steve
2003 Discovery 2a
In better care:
1992 Defender
1963 Series IIa Ambulance
1977 Series III Ex-Army
1988 County V8
1981 V8 Series 3 "Stage 1"
REMLR No. 215
Bookmarks