## Fascinating numbers...

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- Fascinating numbers...

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Fascinating numbers...

05-02-2015 9:34 PM

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Quote Choose a four digit number (the only condition is that it has at least two different digits).

Arrange the digits of the four digit number in descending then ascending order.

Subtract the smaller number from the bigger one.

Repeat.

Eventually you’ll end up at 6174, which is known as Kaprekar’s constant. If you then repeat the process you’ll just keep getting 6174 over and over again.

Quote Take 1 + √3 and 1 − √3 and add them together - what do you get? It works for all values of x (1 + √x and 1 − √x)

Quote 111,111,111 × 111,111,111 = 12,345,678,987,654,321

Quote 18 is the only positive number that is twice the sum of its digit

Any more...?

**Forum Moderator** and ** Customer***Courage is resistance to fear, mastery of fear, not absence of fear - Mark Twain*

He who feared he would not succeed sat still

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Re: Fascinating numbers...

05-02-2015 10:41 PM

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153 is also the sheet number of the Michelin map of the Western Sahara, there is an strange club called the 153 club ,of which there were 153 members, to be eligible for membership you must have traveled across Michelin map 153.

153 is the sum of the first 17 integers and the sum of factorial 1-5 ie 1!+2!+3!....5!............

Broken down to variations of 1 and 5 and 3

153 + 513 = 666

315 + 351 = 666

135 + 531 = 666

and so on

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Re: Fascinating numbers...

05-02-2015 11:08 PM

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http://www.numberphile.com/

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Re: Fascinating numbers...

06-02-2015 1:44 AM

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The sum of all entries in an n×n multiplication table equals [n(n+1)/2]^2.

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Re: Fascinating numbers...

06-02-2015 11:43 AM

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Re: Fascinating numbers...

06-02-2015 12:09 PM

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Re: Fascinating numbers...

06-02-2015 1:14 PM

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At any given moment in the universe many things happen. Coincidence is a matter of how close these events are in space, time and relationship.

Opinions expressed in forum posts are those of the poster, others may have different views.

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Re: Fascinating numbers...

06-02-2015 1:17 PM

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__ Customer__ and Forum Moderator. Windows 10 Firefox 64.0 (64-bit)

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Re: Fascinating numbers...

06-02-2015 1:35 PM

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Quote from: Mav Spurred on from the arithmetical thread I thought I'd start one on how fascinating numbers can be...

Quote Take 1 + √3 and 1 − √3 and add them together - what do you get? It works for all values of x (1 + √x and 1 − √x)

That isn't particularly surprising seeing as you are simply doing the following

1 + 1 + √x - √x or even simpler

1 + 1

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Re: Fascinating numbers...

06-02-2015 1:44 PM

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1+3 =

**4**+ 5 =

**9**+ 7 =

**16**+ 9 =

**25**etc.

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Re: Fascinating numbers...

06-02-2015 7:23 PM

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(n + 1)^2 = n^2 + (2n + 1)

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Re: Fascinating numbers...

06-02-2015 8:33 PM

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Re: Fascinating numbers...

07-02-2015 12:55 AM

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Quote With this simple short cuts you can find out a number is divisible by a given number Divisible by 2: A number is divisible by 2, if its unit’s digit is any of 0, 2, 4, 6, 8. Example: 6798512

Divisible by 3: A number is divisible by 3, if sum of its digits divisible by 3. Example : 123456 1+2+3+4+5+6 = 21 21 is divisible by 3 so 123456 is also divisible by 3

Divisible by 4: if the last two digits of a given are divisible 4, so the number can be divisible by 4. Example : 749232 Last two digits are 32 which are divisible by 4 so the given number is also divisible by 4

Divisible by 5: If unit’s digit of a number is either ‘0’ or ‘5’ it is divisible 5. Example : 749230

Divisible by 6: If a given number is divisible by 2 and 3 (which are factors of 6), then the number is divisible by 6. Example : 35256 Unit’s digit is 6 so divisible by 2 3+5+2+5+6 = 21 so divisible by 3 So 35256 divisible by 6

Divisible by 8: if last 3 digits of a given number is divisible 8, then the given number is divisible 8. Example: 953360 360 is divisible by 8, so 953360 is divisible by 8

Divisible by 9: A number is divisible by 9, if sum of its digits divisible by 9. Example : 50832 5+0+8+3+2 = 18 divisible by 9 so 50832 divisible by 9

Divisible by 10: A number is divisible 10, if it ends with 0. Example : 508320

Divisible by 11: A number is divisible by 11,if the difference of sum of its digits at odd places and sum of its digits at even places , is either 0 or a number divisible by 11. Example : 4832718 (sum of digits at odd places ) – (sum of digits at even places) =(8+7+3+4)-(1+2+ = 11 which is divisible by 11. So 4832718 is divisible by 11.

I hope this simple tricks, will be very helpful to solve math’s homework problems easily.

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