Saturday, January 06, 2007

Playing With Numbers

OK, today I was in the shower, playing with numbers in my head, when I had a sort of revelation about the number 6. I've finally finished a set of thoughts about 3, 6 and 9.

For 3
Pick a number, any number. Now split the whole sequence of digits into 1-digit numbers. If you don't get a 1-digit number after adding, keep doing it again until you do. If you end up with a 3, 6 or 9, you started with a multiple of 3.

For 6
Take the number you started with. If it's even and it fits what you did for 3, it's also a multiple of 6.

For 9
OK, now you take a number, you separate it into individual digits and add them together. If the number you end up with has more than 1 digit, do it again until you do end up with a 1-digit number. If that number is 9, you started with a multiple of 9.

1 comment:

Harley said...

Here's an example if you want one:

Start with 73575

7+3+5+7+5=27

2+7=9

So 73575 is a multiple of 3 and 9.