Primal days

mrwrite · 2013-04-06 20:15:20

I noticed that the program "Calendar Magic" now comes with math utilities. It is a free download.
One of them is Prime Calculator. I typed in Saturday's date as "462013" and discovered it is a prime. Also, 4062013 is prime, if you prefer a leading zero.

So far there have been 10 prime days this year.
192013, 1142013, 232013, 2112013, 2122013, 2272013, 322013, 372013, 3312013, and 462013.
The next one is 492013. (Also 4092013, if you prefer a leading zero.)

Curious thing. After December 23, 2013, there will not be another prime-day until Thursday, January 5, 2017. That would be 1,108 days without a prime day.

I am not suggesting we stockpile primes, but it wouldn't hurt to keep some around when needed.

bobbym · 2013-04-06 20:20:06

Hi mrwrite;

Welcome to the forum.

1142013 is not a prime.

3 x 151 x 2521 = 1142013

Agnishom · 2013-04-06 20:21:14

Nice Information, thank you.
Do you have the link to the math utilities?

mrwrite · 2013-04-06 20:42:01

Do you have the link to the math utilities?

Calendar Magic is a tool for calendars. It has virtually all the calendars in use today. (Even Persian.)
Calendar Magic also has a few Math tools. The program is available at download.cnet.com and I need to warn you that cnet now includes options to download toolbars and other useless bloatware with EVERY download. You download a program LINK. Then click on the link which starts the real download, and tries to entice you to add extras. Each is optional, but you need to read the screens and follow instructions to NOT download them. So, visit downloads.cnet.com and search for Calendar Magic. It works on the PC only.

1142013 is not a prime.

You are right! A most embarrassing error.

mrwrite · 2013-04-07 14:15:16

The full list for 2013 is:
192013
232013
2112013
2122013
2272013
322013
372013
3312013
462013
492013
4222013
4302013
582013
5142013
5262013
5272013
642013
6202013
7122013
7212013
7302013
822013
852013
862013
8172013
8202013
8302013
942013
9142013
9192013
9202013
9222013
9252013
1062013
10132013
10152013
10222013
10252013
10272013
1192013
11142013
12222013
12232013
11302013
11212013
12112013

mrwrite · 2013-04-07 20:43:53

Agnishom, in a different forum you say:

But first I need to make a list of primes up to ten digits. I am scared about that part

Why do you need the 4,118,054,813 primes? The first 50 million are on the internet. You can download them.

Agnishom · 2013-04-08 01:55:21

Hello

You could have posted there.
I need them because I had to express a ten digit number as a sum of two prime numbers.
Presently I have a list of 2063689 primes

mrwrite · 2013-04-08 07:57:18

If you need to express a ten digit number as the sum of two primes, a list of primes up to NINE digits would suffice (except for 10 digit primes). You only need 50,847,534 primes to make a sum of all possible 10 digit compound numbers. That is available free online.

bobbym · 2013-04-08 08:11:14

Hi;

The largest nine digit prime is 999999937 so he would only be able to express numbers up to 1999999874, about a fifth of them. He needs a larger table than that.

mrwrite · 2013-04-09 09:19:54

Right! I get it now. He would need a two and 10 digit primes to test all the even numbers from 2,000,000,002 to 4,999,999,998. Likewise a single digit (odd) prime and a 10 digit prime for the odd numbers in range.

Note to Agnishom: How many computer do you have for the project?

Agnishom · 2013-04-11 15:27:43

One! Just a normal computer anybody uses

I am not a millionaire!

But I think I can split up almost every ten digit number using a table of primes of 8 digits

bobbym · 2013-04-11 16:46:58

How many are left out? Did you count them?

Agnishom · 2013-04-11 16:48:33

How many are left out from the total of what?

bobbym · 2013-04-11 16:50:57

How many ten digit numbers are not representable by your method?

Agnishom · 2013-04-11 16:57:25

I really don't think there is any such number.
Do you think so?

mrwrite · 2013-04-11 21:07:53

One! Just a normal computer anybody uses
I am not a millionaire!

I am not a millionaire either. But I have access to two computers. I was wondering if you were splitting the task between more than one computer.

For example one computer could resolve the EVEN 10 digit numbers between 2,000,000,014 and 9,999,999,874. Another computer could resolve the Even numbers between 1,000,000,0002 to 2,000,000,012.
Because the first would be a 2 and a ten digit prime and there are 84,106,688 primes that would qualify.
.
If you use a thumb drive for data and results, you could accomplish the first task in less than a day. (Depending on the speed and computer language you use. Using BASIC language my computer can do about 26,000 results in a second.)

mrwrite · 2013-04-11 21:29:11

I really don't think there is any such number.
Do you think so?

4,986,195,733 is a ten digit number that has only 70,619 and 70,607 as factors and no other prime factors except for 1.

Last edited by mrwrite (2013-04-11 21:38:52)

Agnishom · 2013-04-12 00:48:12

mrwrite wrote:

I really don't think there is any such number.
Do you think so?
4,986,195,733 is a ten digit number that has only 70,619 and 70,607 as factors and no other prime factors except for 1.

Do you even have the idea what I am planning to do?

mrwrite · 2013-04-12 08:24:02

Do you even have the idea what I am planning to do?

My only clue to your plan is what you said earlier:

...express a ten digit number as a sum of two prime numbers.

and

...I think I can split up almost every ten digit number using a table of primes of 8 digits

There are 4,238,564 eight digit primes.
There are 25 primes less than 100.

IF you multiply all eight digit primes by all two (and one) digit primes you get
only over 105 million compound numbers. Minus the answers that appear as nine-digit results, you get about 100+ million ten digit numbers.
(This does not include the 404+million 10 digit prime numbers.)

To get all ten-digit numbers made of two primes, you would need prime combinations of one digit and nine digits, one digit and ten digits, two digits and eight digits, three digits, and eight digits ... up to five digits and five digits.

The reason I ask about your computer, is because the results would take a huge amount of space on the computer. I would do it in stages using a six gig thumb drive. Then, copy the results off the thumb drive after each success. Sort them later.

Last edited by mrwrite (2013-04-12 09:13:03)

Agnishom · 2013-04-12 14:02:23

Okay, but why are you trying to multiply?

Have you seen how I do it?

mrwrite · 2013-04-12 15:12:18

That's right, you said SUM of two primes. This sounded so much like the theory of data pointers with primes, I assumed multiplication.

Agnishom · 2013-04-12 16:30:00

Yep

By the way, why don't you post somewhere outside THIS thread?

Math Is Fun Forum

#1 2013-04-06 20:15:20

Primal days

#2 2013-04-06 20:20:06

Re: Primal days

#3 2013-04-06 20:21:14

Re: Primal days

#4 2013-04-06 20:42:01

Re: Primal days

#5 2013-04-07 14:15:16

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#6 2013-04-07 20:43:53

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#7 2013-04-08 01:55:21

Re: Primal days

#8 2013-04-08 07:57:18

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#9 2013-04-08 08:11:14

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#10 2013-04-09 09:19:54

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#11 2013-04-11 15:27:43

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#12 2013-04-11 16:46:58

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#13 2013-04-11 16:48:33

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#14 2013-04-11 16:50:57

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#15 2013-04-11 16:57:25

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#16 2013-04-11 21:07:53

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#17 2013-04-11 21:29:11

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#18 2013-04-12 00:48:12

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#19 2013-04-12 08:24:02

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#20 2013-04-12 14:02:23

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#21 2013-04-12 15:12:18

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#22 2013-04-12 16:30:00

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