### Fun With the Number 9

I hope this isn't a sign that I'm running out of blog material, but the best thing I can think about writing is some fun (?!) mathematical tricks.

Consider the following:

All ten digits, from lowest to highest:

0 1 2 3 4 5 6 7 8 9

All ten digits, from highest to lowest:

9 8 7 6 5 4 3 2 1 0

What do you get when you put them together;

0 1 2 3 4 5 6 7 8 9

9 8 7 6 5 4 3 2 1 0

Multiples of Nine!

Even weirder,

**when you add up all the digits of a multiple of nine, you get a multiple of nine**.

For Example:

9 x 14 = 126. 1 + 2 + 6 = 9

9 x 4258 = 38322. 3 + 8 + 3 + 2 + 2 = 18

9 x 2156754862 = 19410793758. 1 + 9 + 4 + 1 + 0 + 7 + 9 + 3 + 7 + 5 + 8 = 54

Now I got to go wash out my pocket protector for the big D & D game tomorrow. Bye.

## 1 Comments:

I'm pretty sure that it's a general rule that in any number base N, then N-1 has the properties you've shown.

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