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Long chain (Posted on 2015-04-10)

Create a chain of consecutive digits starting with 1 and following 9 by 0: 123456789012345...

How many digits are needed to obtain the 1st prime number?

See The Solution Submitted by Ady TZIDON

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Computer says... (spoiler)

| Comment 4 of 7 |

chain=1;i=1;
While[!PrimeQ[chain],chain=10*chain+Mod[++i,10]];
Print[chain];Print[IntegerLength[chain]];

12345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890
12345678901234567890123456789012345678901234567890
123456789012345678901

171

Posted by Harry on 2015-04-11 06:59:28

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