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-   -   What minimum exponent would give 100M digit prime? (https://www.mersenneforum.org/showthread.php?t=13313)

 odin 2010-04-18 01:21

What minimum exponent would give 100M digit prime?

Hello All,

What minimum exponent value would give a 100M digit prime?

Also is there a calculator on the internet or that I could download that could give me the specific number that any exponent I use in the formula 2^P - 1?

Like to calculate the value of:

2^49254458 - 1?

Of course my computer's calculator gives infinity!!!!!

Thanks.

[url]http://mersenne-aries.sili.net/digits.php[/url] calculate number of digits from an exponent

i think it something above 332,000,000 for the exponent to give a 100M digit mersenne number.

 odin 2010-04-18 01:28

[QUOTE=CADavis;212224][url]http://mersenne-aries.sili.net/digits.php[/url] calculate number of digits from an exponent

i think it something above 332,000,000 for the exponent to give a 100M digit mersenne number.[/QUOTE]

Thanks. You are right. I don't think I will be winning that prize. lol

 lfm 2010-04-18 02:22

[QUOTE=CADavis;212224][url]http://mersenne-aries.sili.net/digits.php[/url] calculate number of digits from an exponent

i think it something above 332,000,000 for the exponent to give a 100M digit mersenne number.[/QUOTE]

Its pretty easy if you have a proper calculator. Just 1e6*ln(10)/ln(2)=3321928.09 or so.

 Uncwilly 2010-04-18 05:58

332192831 is the first prime that is 100 M digits.
There is a thread for those that TF'ing those in the range.

 10metreh 2010-04-18 11:05

[QUOTE=Uncwilly;212247]332192831 is the first prime that is 100 M digits.[/QUOTE]

[pedant]No, it's the first prime p such that log[sub]10[/sub](2[sup]p[/sup]-1) > 99,999,999.[/pedant]

 lfm 2010-04-18 11:09

[QUOTE=lfm;212230]Its pretty easy if you have a proper calculator. Just 1e6*ln(10)/ln(2)=3321928.09 or so.[/QUOTE]

oops should be 1e8!

 Uncwilly 2010-04-18 13:57

[QUOTE=10metreh;212278][pedant]No, it's the first prime p such that log[sub]10[/sub](2[sup]p[/sup]-1) > 99,999,999.[/pedant][/QUOTE]
You didn't see my [lazy shorthand][/lazy shorthand]?

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