a) Vì Ư (24) = {1; 2; 3; 4; 6; 8; 12; 24};
Ư (40) = {1; 2; 4; 5; 8; 10; 20; 40};
=> ƯC (24;40) = {1;2;4;8}.
b) Vì B (2) = {0; 2; 4; 6; 8; 10; 12; 14; 16; 18; 20; 22; 24;... };
B(8) = {0,8; 16; 24; 32; 40;...}.
=> BC (2;8) = {0;8; 16;24;32;...}
c, Ư(20) = {1;2;4;5;10;20}
Ư(30) = {1;2;3;5;6;10;15;30}
=> ƯC (20; 30) = {1;2;5;10}
d, B(10) = {0;10;20;30;40;...}
B(15) = {0;15;30;45;60;...}
=> BC = {0;30;60;90;...}