mental math

Ever since I was in grade school, I have had this tendency to look at numbers, say, on a clock or a license plate and add them together. For instance, right now it's 9:43 a.m. I might start by adding the individual digits together until I'm only left with a single number. It goes something like this...

9:43
9+4+3=16
1+6=7

And then I'll wonder whether I'd get a different results if I changed how I combined the numbers.

9:43
(9+4)=13
1+3=4
4+3(the original 3 from the time)=7

I try to think of different ways the numbers could be combined, typically only using addition) to see whether the result is always the same. The goal is typically to get down to a single digit. Let's say a license plate was 25E 627.

2+5+6+2+7=22
2+2=4

But then I'll switch the method so that with each addition has to be added down to 1 digit before the next number can be added in. I'll bold the original numbers below.

2 | 5 | 6| 2 | 7
2+5=7
7+6=13
1+3=4
4+2=6
6+7=13
1+3=4

More often than not, no matter how I combine the numbers, the result is the same. I find that fascinating.

Am I the only one who does this? I suspect it's not something most people do when they look at strings of numbers. You can just file this away as thing #174390 that is quirky about Melissa. Or, to simplify...

1+7+4+3+9+0=24
2+4=6

:)