So you may think I'm a little weird after you read this - but that's okay. I am weird in many ways, and proud of it. I do a little thing with numbers in my head. Perhaps it started when I was a child, to ward off boredom in never-ending Bible study sessions, or to ward off sadness during a difficult period of my childhood. However it started, it is something I just discover my mind doing - I never decide to do it. I would not call it an obsession, I just find myself doing little math calculations with the numbers on license plates as I drive along or sit in traffic. (Please try and restrain the laughter - you have to see what I discovered doing this!) So, I'm not really paying attention as I do this little math thing - I think it is just a part of my mind that does this - there are other parts of my mind that talk, drive, plan, occasionally curse at rude drivers, etc. But here is what I discovered just by accident:
Take ANY number and add all of the digits in it together, e.g. the number 48; 4+8=12; then add the digits in the answer (12) together until you arrive at a single digit, in this case 1+2=3. Then subtract the single digit you get from the original number you chose 48-3=45. Then add all the digits in the answer together 4+5=9. (If there is more than one digit in your answer after subtracting, add those numbers together, until you get one number).
Guess what: No matter what number you choose at the beginning (adding its digits together then adding the digits in answer together til you have one number. Subtract that one digit from the original number and) you will ALWAYS get the answer/number 9.
Okay, let's try it a few times:
1111 ~ 1+1+1+1=4 ~ 1111-4=1107 ~ 1+1+0+7=9
5555 ~ 5+5+5+5=20 ~ 2+0=2 ~ 5555-2=5553 ~ 5+5+5+3=18 ~ 1+8=9
364 ~ 3+6+4=13 ~ 1+3=4 ~ 364-4=360 ~ 3+6+0=9
1972 ~ 1+9+7+2=19 ~ 1+9=10 ~ 1+0=1 ~ 1972 -1=1971 ~ 1+9+7+1=18 ~ 1+8=9
68 ~ 6+8=14 ~ 1+4=5 ~ 68-5=63 ~ 6+3=9
97 ~ 9+7=16 ~ 1+6=7 ~ 97-7=90 ~ 9+0=9
69 ~ 6+9=15 ~ 1+5=6 ~ 69-6=63 ~ 6+3=9
8634 ~ 8+6+3+4=21 ~ 2+1=3 ~ 8634-3=8631 ~ 8+6+3+1=18 ~ 1+8=9
Now isn't that weird? Follow the instructions with any number you can come up with, and the answer will ALWAYS be 9.
Now this may not be news to those of you out there who are mathematicians, but it was a surprise to me and to everyone I demonstrated it to. I know that this works this way, I do not know why it works out to 9 every time. If anyone knows the why - please explain it to me.
In my excitement and hubris, I thought I had discovered this mathematical oddity. But my husband brought me back down to earth saying it had to be a known phenomenon and sure enough, he was right. I googled it and there it was - already known and clearly described. Whatever . . . I had fun making my own little discovery, and you can now boggle the minds of a few people by showing them this too.
There are a couple of people in my family who do not believe I stumbled across this by myself. They always giggle and say I must have found it on the internet. I did not. I noticed it all by my little self and even if it does make me weird, it was an exciting moment of discovery. Always did favour the number 9.