# Prime Directive ?

By pgn

@pgntwo (20728)

Derry, Northern Ireland

May 17, 2017 3:06pm CST

Here's one for the mathematicians amongst us.
Most people know that a prime number is only divisible by itself or by 1, for example, the number "31".
So if you keep placing a 3 in front of 31, (331; 3,331; 33,331...), it stays prime until it reaches 333,333,331 (which factors into 19,607,843 x 17).
Why is that, I wonder...?
PS. I tested out some of the possibilities on WolframAlpha, a mathematical search engine, adding or removing a 3 each time:

To see full output on this page you need to enable JavaScript in your browser. Computing... Input: Result: Computing... Give us feedback » Computed by Wolfram Mathematica View Wolfram|Alpha in: Mobile | Standard © 2017 Wolfram Alpha LLC Terms of Use |

16 people like this

16 responses

@arthurchappell (27656)

• Preston, England

18 May

@pgntwo maths usually causes my mind to disintegrate

4 people like this

@pgntwo (20728)

• Derry, Northern Ireland

18 May

Ah, a numerohobe, or an arithmophobe?

FearOf.net This website is dedicated to fears and phobias. It contains a large list of phobias and teaches how to cope with and ultimately cure your fear. You can also learn more about phobia symptoms and what fear is. Support my work by sharing this phobi

3 people like this

@DesirousDreamer (18563)

• Peoria, Arizona

17 May

I feel like someone has to be very bored to figure that out haha! But interesting nonetheless!

3 people like this

@Poppylicious (8452)

•

18 May

I'm afraid that I completely switched off when you mentioned the word mathematician. *makes the sign of the cross*

3 people like this

@Susan2015 (19232)

• United States

20 May

Math was my absolute worst subject in school.

2 people like this

@DaddyEvil (22322)

• Aurora, Missouri

20 May

Hmmm... I am nowhere close to a mathematician, pgn... (I'm lucky I know what a prime number is, let alone most things involving math!)
Yes, I can add, subtract, multiply and divide in my head quite quickly, but you really should talk with @sishy7 about things like this! LOL!

1 person likes this

@DaddyEvil (22322)

• Aurora, Missouri

21 May

@pgntwo Hmmm... not sure about that, pgn... maybe just the greedy people who hire them!

2 people like this

@pgntwo (20728)

• Derry, Northern Ireland

21 May

@DaddyEvil It could be - but the controllers must be hot with numbers too, I'd guess.

1 person likes this

@much2say (36282)

• United States

17 May

My daughter has recently had to deal with good 'ol prime numbers and factoring in her math class . . . math makes her head hurt as much as it does mine (especially the way they teach it these days ). I wonder if her teacher knows about this one .

1 person likes this

@Mike197602 (13391)

• Worcester, England

17 May

I got a few A's in GCSE's and A levels...maths was not among the A's
PS...this discussion reminded me of Optimus Prime from the transformers...when pissed I look at his end speech from the film on youtube

1 person likes this

@Mike197602 (13391)

• Worcester, England

17 May

@pgntwo I like the linkin park track and I'm a fan of the megan fox/shia lebouf, or whatever his name is, films.

3 people like this

@Mike197602 (13391)

• Worcester, England

17 May

The link is there...it is waiting

3 people like this

@pgntwo (20728)

• Derry, Northern Ireland

18 May

I had a play with this number series on the mathematical search engine, WolframAlpha, here's a sample - add or remove 3s until it starts to be "not prime":

1 person likes this