Statistics on primes

[daydreamer]

Hi
I am probably not the only one who like statistics and curves
After looking at list with loads of primes
Would be interesting create statistics for last digits is of number is a prime

[raymond]

Only the terminating digits 1, 3, 7 and 9 can be considered for prime numbers (the only exceptions being the actual prime numbers 2 and 5).

If your sample is large enough, each of those four terminating digits would likely be close to 25%.

[daydreamer]

Only the terminating digits 1, 3, 7 and 9 can be considered for prime numbers (the only exceptions being the actual prime numbers 2 and 5).

If your sample is large enough, each of those four terminating digits would likely be close to 25%.

Very big primes BCD it saves lot of CPU cycles with determine ending with even number and '5' using
 test al,1 and cmp al,'5' faster than idiv 5
Or keyboard input string ,process last digit can skip even conversion to integer and rest of prime testing


Take a look at some of two last digits are the same
1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20
1–20   2   3   5   7   11   13   17   19   23   29   31   37   41   43   47   53   59   61   67   71
21–40   73   79   83   89   97   101   103   107   109   113   127   131   137   139   149   151   157   163   167   173
41–60   179   181   191   193   197   199   211   223   227   229   233   239   241   251   257   263   269   271   277   281
61–80   283   293   307   311   313   317   331   337   347   349   353   359   367   373   379   383   389   397   401   409
81–100   419   421   431   433   439   443   449   457   461   463   467   479   487   491   499   503   509   521   523   541
101–120   547   557   563   569   571   577   587   593   599   601   607   613   617   619   631   641   643   647   653   659
121–140   661   673   677   683   691   701   709   719   727   733   739   743   751   757   761   769   773   787   797   809