Thursday, October 30, 2008

Thursday Thirteen - Numbers!

Sometimes, I just browse the internet aimlessly for the express purpose of stumbling upon something interesting that I would never have thought of to search. Today, I came upon numbers and followed that train of thought.

Here are 13 Interesting Facts About Numbers & Maths

1) 111,111,111 x 111,111,111 = 12,345,678,987,654,321.

2) 1234567.9 x 9 = 11111111

3) Multiply 37,037 by any single number (1-9), then multiply that number by 3. Every digit in the answer will be the same as that first single number.
For example: 37,037 x 5 = 185,185; 185,185 x 3 = 555,555

4) 2 is the only even prime.

5) 18 is the only number that is twice the sum of its digits.

6) 81 is the square of the sum of its digits.

7) 12+3-4+5+67+8+9=100

8) A Googol has 100 zeros.

9) 25 (5 x 5) is the smallest square that can be written as a sum of 2 squares
(3 x 3 + 4 x 4).

10) 40 is the only number whose letters are in alphabetical order.

11) 89 = 8^1 + 9^2 (What I mean is 8 to the power of 1 and 9 to the power of 2.)

12) Pi has been calculated to 2,260,321,363 digits. The billionth digit in Pi is 9.

13) This one is for people like me who can't remember their multiplication tables.

You can use your fingers for 1 x 9 to 9 x 9.

Hold both hands out in front of you, palms facing away. For 1 x 9, bend the little finger on your left hand. You're left with 9 fingers to the right of that little finger. Of course, you probably didn't need to use this method to get the answer to 1 x 9.

For 2 x 9, bend the ring finger on your left hand. Now there is 1 fingers to the left of the ring finger and 8 to the right of it. The answer is 18.

Jumping to 5 x 9. Bend your left thumb. Now you have 4 fingers to the left of your thumb and 5 to the right of it letting you know the answer is 45.

Its so much easier to explain if you could all just see my fingers! Try it out anyway :)

13 comments:

John said...

Numbers are fun! Thanks for sharing.

Anonymous said...

your maid & driver in palembang cannot even count with their fingers!

Bilbo said...

That was fun, even though I'm seriously mathematically challenged. The thing about using both hands to do the 9-tables is really neat...school kids love it. All this makes me homesick for the Numeric Life blog that went offline a year or more ago.

Mike said...

If you want to see the first million digits of pi go to an old blog of mine http://pipieces.blogspot.com/ .

And yes the billionth digit is 9. My BVN number is 9,643,883,119. Digits one billion through one billion and nine. One of these days (in my spare time) I'm going to start selling BVN numbers. I might give them away to my friends.

BTW, you are here by elected our new 'numbers person'.

Amanda said...

When I posted last night, I wasn't sure if people would enjoy this type of trivia about numbers.

I'm glad you've all enjoyed it.

Mike, I took a look at your other blog. Impressive, but what gave you such an idea?! Did you double check for typos :)

Jean-Luc Picard said...

What interesting numerical facts. I wonder who thought of those!

John said...

to go along with #1:
1x1=1
11x11=121
111x111=12321
1111x1111=1234321
11111x11111=123454321
111111x111111=12345654321
1111111x1111111=1234567654321
11111111x11111111=123456787654321
and of course
111111111x111111111=12345678987654321

Mike said...

I haven't talked about my pi blog in awhile. I think I just came up with a post for tomorrow.

As far as typo's. I didn't check all the numbers. I just checked all the 5's to see if they were in the right places and then just assumed the rest were correct. (HA!)

Amanda said...

OMG! Apologies everybody. I've fixed the typo in number 11.

John, that is very cool. I showed it to my mom and she was fascinated, as was I.

Bilbo said...

John, you need to get that "1" key on your keyboard unstuck...

Gilahi said...

I think you may have a typo in #2 as well. It appears you may have omitted a digit from the product. Otherwise, multiplying by 9 nets you a smaller number than you began with.

Amanda said...

You're right Gilahi. Thank you for reading with so much attention to detail. I do appreciate it.

I did a straight Cut and Paste but now that I do the division on the 11111111, I get 1234567.9.

Thanks again.

Mike said...

That's an idea. Put some math errors out there and see if anybody can find them.