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#1 2011-03-01 02:55:32

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Let's make triangular numbers.

The first triangular number is 1.
To continue this thread, simply
add 2, then 3, then 4, on forever
to make triangular numbers.

So I'll go first:

1
(one)


igloo myrtilles fourmis

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#2 2011-03-01 13:28:07

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

3 is triangular and prime.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#3 2011-03-02 05:17:16

G-man
Member
Registered: 2011-02-28
Posts: 16

Re: Let's make triangular numbers.

6  Its triangular & first composite which isn't a square.


Maths!......sleep

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#4 2011-03-02 09:41:30

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

10 - The number of balls in a 10 ball rack. The first 2 digit triangular number! Also it is larger than 1 - 9 and has a zero in it.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#5 2011-03-02 12:31:13

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

15
  5 x (6/2)


igloo myrtilles fourmis

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#6 2011-03-02 15:17:51

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

21 everybody's favorite number


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#7 2011-03-02 15:43:46

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,552

Re: Let's make triangular numbers.

28: has factors 1, 2, 4, 7, 14, 28 and reminds me of February


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#8 2011-03-02 15:53:48

G-man
Member
Registered: 2011-02-28
Posts: 16

Re: Let's make triangular numbers.

36
square of product of first two consecutive primes.


Maths!......sleep

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#9 2011-03-02 21:13:39

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

45 - ( Colt ) the best automatic ever made.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#10 2011-03-03 15:53:14

G-man
Member
Registered: 2011-02-28
Posts: 16

Re: Let's make triangular numbers.

55..........dunno


Maths!......sleep

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#11 2011-03-03 18:17:35

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

66 - the 11 the triangular number and the name of a now infamous highway here in the southwest.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#12 2011-03-06 02:21:55

matthen
Member
Registered: 2011-03-06
Posts: 8

Re: Let's make triangular numbers.

78

note these triangular numbers go:
...,45,55,66,78,91, quite cool that 4,5,6,7,8,9 appear in order with no interruptions!

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#13 2011-03-06 05:49:43

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

91 The most powerful triangular number and the one that wants to be a square the most. Also it is the only one that is 7 * 13.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#14 2011-03-22 11:31:19

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

105=14+91     
(14/2)*15


igloo myrtilles fourmis

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#15 2011-03-22 12:48:39

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

The 15th triangular number is 120. Which is also 5!.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#16 2011-03-22 13:58:55

G-man
Member
Registered: 2011-02-28
Posts: 16

Re: Let's make triangular numbers.

136.........1, 3 & 6 are first 3 triangle numbers.


Maths!......sleep

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#17 2011-03-22 14:28:21

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

153

Is a square away from 2 squares. 12^2 + 3^3 = 153 and 13^2 - 4^2 = 153


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#18 2011-04-05 02:21:55

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

171
     153 + 18 = 171
     (19 x 18) / 2


igloo myrtilles fourmis

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#19 2011-04-05 02:50:56

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

190

The famous 190 Bowery St.

http://nymag.com/realestate/vu/2008/09/50481/


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#20 2011-04-16 08:29:10

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

210
    210 = 190 + 20
       210 = 14 x 15 = (21 x 20) / 2 on this post # 20.


igloo myrtilles fourmis

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#21 2011-04-16 08:51:43

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

231

One of the permutations of 123.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#22 2011-04-16 11:34:54

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

253
   253 = 231 + 22 = (1 + 22)+(2 + 21)+...(9 + 14)+(10 + 13)+(11 + 12)
                          = 11 x 23 = (23 x 22) / 2
             This triangular number can form a digital triangle with 22 rows in 3 angles differing by 120 degrees.


igloo myrtilles fourmis

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#23 2011-04-16 14:40:42

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

276

And that is real close to 253.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#24 2011-04-17 12:13:04

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,566

Re: Let's make triangular numbers.

300

     Yeah 300!!!!   276 + 24.    (25 x 24) / 2       A triangle with 24 rows.


igloo myrtilles fourmis

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#25 2011-04-17 12:20:22

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,615

Re: Let's make triangular numbers.

325 which is 3*5 - 2 = 13.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

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