Plate Number Arithmetic

When I’m commuting to school or back home, I can hardly do anything but think. Well, I can also eat some drive-thru food, engage in a few catnaps, or talk to a friend who is also commuting, but most of the time I can only reflect on something. However, whenever I’m not thinking of anything, or whenever I simply choose not to think of anything that will just make me worry about it, I usually add the three digits of the plate numbers of nearby vehicles that pass ours by. Naturally, the sum of the three digits should not be less than 3, nor should it be higher than 27. But here’s a neat trick I discovered out of boredom during my tricycle travels. Let me call it Jules’s Theorem (bwahahaha!):

Anyway, suppose you have a plate number with numbers taking the form of:

A B C . 9 1 X, where X is any number from 0 to 9 (duh, hehe)

If you wish to add the numbers up, just remove the number 9 and voila! You get the sum of the three digits, which is 1 X.

For example, if my plate reads WCS.912, the sum of the digits of my plate number is 12 (I just removed the 9) because 9 + 1 + 2 = 12. Similarly, for a plate that reads XFJ.918, just remove the 9 and you get 18 as the sum of the digits of that plate.

Hehe imagine what boredom can do.