Numerele care nu sunt prime se numesc numere compuse.
Sau : numerele care au cel putin trei divizori se numesc numere compuse.
a. 4,6,8,9,10
b.10, 12,14,15,15,18,20,21,22,23,25,26,27,28,30
c. 20,21,22,23,25,26,27,28,30,32,33,34,35,36,38,39,40,42,44,45,46,48,48,50
d. 40,42,44,45,46,48,48,50,52,54,55,56,58,60,62,63,64,65,66,68,69,70
e. 60,62,63,64,65,66,68,69,70,72,73,74,75,76,78,80,81,82,84,85,86,88,
90,92,94,95,96,98,100