Răspuns:
Explicație pas cu pas:
abc= 100a+10b+c
a) pt a=1 => ab=11, 13, 17, 19 => b=1, 3, 7, 9 => abc=111, 113, 117, 119, 131, 133, 137, 139, 171, 173, 177, 179, 191, 193, 197, 199
pt a=2 => ab=23, 29 => b=3, 9 => abc= 233, 239, 293, 299
pt a=3 => ab=31, 37 => b=1, 7 => abc=311, 317, 371, 377
pt a=4 => ab=41, 43, 47 => b= 1, 3, 7 => abc=411, 413, 417, 431, 433, 437, 471, 473, 477
pt a=5 =>ab=53, 59 =>b=3, 9 => abc=533, 539, 592, 599
pt a=6 =>ab=61, 67 =>b= 1, 7=> abc=611, 617, 671, 677
pt a=7 => ab=71, 73, 79 =>b=1, 3, 9 => abc=711, 713, 719, 731, 733, 739, 791, 793, 799
pt a=8 =>ab=83, 89 =>b=3,9 => abc=833, 939, 893, 899
pt a=9 =>ab=97 =>b=7=> abc=977
