perplexus.info :: Numbers : Never prime! (2)

Never prime! (2) (Posted on 2010-09-04)

The value of the smallest positive base ten integer that cannot be changed into a prime by changing a single digit was determined in Never prime!.

Determine the respective minimum values of a positive base N integer P that cannot be changed into a prime by changing a single digit, whenever N is a positive integer with 3 ≤ N ≤ 16, but N ≠ 10.

Note: P cannot contain any leading zero, and the first digit of P (reading left to right) cannot be changed to a zero.

Submitted by K Sengupta

Rating: 5.0000 (1 votes)

Solution: (Hide)

Base 3; P = 7 (21); 24 (220) Base 4; P = 24; 120 Base 5; P = 67 (90); 232 (330) Base 6; P = 90; 230 Base 7; P = 119; 230 Base 8; P = 200; 310 Base 9; P = 117; 140 Base 11; P = 319; 270 Base 12; P = 528; 380 Base 13; P = 1131; 690 Base 14; P = 1134; 5B0 Base 15; P = 525; 250 Base 16; P = 1328; 530
Justin has succintly derived these values in this location.

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
re(2): solution	Justin	2010-09-05 17:01:28
re: solution	Charlie	2010-09-05 12:14:55
solution	Justin	2010-09-04 19:44:21
solution and observations	Daniel	2010-09-04 19:22:49

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