Tuesday, September 18, 2007

Math Is My Friend

Math, I love math. Rules are rules, 1+1=2. Can't stand English. i before e except after c... WTF??

I can remember numbers, my SS#, my wife’s SS#, my desk phone, office and cell phone numbers, my wife’s cells (2), office and pager numbers. But I have to ask spell check if I spelled squirrel right...

Numbers I just remember, and stuff like this;


Everyone knows if a number is divisible by 2 or 5, right. How about some other numbers?

Dividing by 2

All even numbers are divisible by 2. E.g., all numbers ending in 0,2,4,6 or 8.

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Dividing by 3

Add up all the digits in the number.
Find out what the sum is. If the sum is divisible by 3, so is the number
For example: 12123 (1+2+1+2+3=9) 9 is divisible by 3, therefore 12123 is too!

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Dividing by 4

Are the last two digits in your number divisible by 4?
If so, the number is too!
For example: 358912 ends in 12 which is divisible by 4, thus so is 358912.

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Dividing by 5

Numbers ending in a 5 or a 0 are always divisible by 5.

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Dividing by 6

If the Number is divisible by 2 and 3 it is divisible by 6 also.

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Dividing by 7 (2 Tests, either/or)

Take the last digit in a number.
Double and subtract the last digit in your number from the rest of the digits.
Repeat the process for larger numbers.
Example: 357 (Double the 7 to get 14. Subtract 14 from 35 to get 21 which is divisible by 7 and we can now say that 357 is divisible by 7.

NEXT TEST
Take the number and multiply each digit beginning on the right hand side (ones) by 1, 3, 2, 6, 4, 5. Repeat this sequence as necessary
Add the products.
If the sum is divisible by 7 - so is your number.
Example: Is 2016 divisible by 7?
6(1) + 1(3) + 0(2) + 2(6) = 21
21 is divisible by 7 and we can now say that 2016 is also divisible by 7.

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Dividing by 8

This one's not as easy, if the last 3 digits are divisible by 8, so is the entire number.
Example: 6008 - The last 3 digits are divisible by one, therefore, so is 6008.

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Dividing by 9

Almost the same rule and dividing by 3. Add up all the digits in the number.
Find out what the sum is. If the sum is divisible by 9, so is the number.
For example: 43785 (4+3+7+8+5=27) 27 is divisible by 9, therefore 43785 is too!

8 comments:

ARTEMIS said...

I like math too..but damn!

How about if I just grab a calculator and push the division button. If it comes out even with no little dot in between the numbers, it's divisble by that number! :o)

Jan said...

dnr...math is Greek to me, when it comes to a lot of stuff.

I think you have to be pretty smart to be adept at math.

Isn't it strange how some are great at math but can't spell a lick, and some who can spell up a storm, can hardly add two and two?

Again, I think it comes down to what you really like, don't you?

Or maybe, it's a jean thing...I mean gene thing! LOL

There I go...laughing at my own jokes!:)

Kat said...

If I was going to Hell, for me it would be two things: very, very cold,and filled with MATH - the two things I hate the most, lol! There's very valid reasons I live in the (nice, warm) SOUTH (where it's still in the 80s) and am an ENGLISH major!!!! LOL!!!!!!!!

DNR said...

ARTEMIS – What fun is that??

Jan – defiantly a gene thing

Kat – MATH=HELL Hummm, I’ll have to study that one. I think spelling=HELL. LOL

Dazd said...

Dang...gonna have to print this out for Lil Dazd.

Thanks!

B Matthews said...

Mathematically challenged here. The rain in Spain falls mainly in the plain, and all that good stuff.

Honestly, I had you 'til we got to sevens. That messed me up. Thanks, DNR, now I have a headache.

You left brainer you!! :-D

CavMom said...

Oooooh... I love numbers except when I am working on a large account and the columns of numbers creep into my dreams.

Awakened at 02:00 by a dream that the missing .03 is in the wrong account

...and I cannot get my mind to wander back to the dream of the scantily dressed men who were trying to help me find my way home.

*sigh*

DNR said...

Dazd - glad it will go to good use for someone.

B_Matt - Anything I can do to make your day.

Cavmom - ok, now, that’s just TOO OCD. If I’m +/- $10, I call it good.
Ummm... no scantily dressed men here, just a fat ass biker.