- $ B = \\\left\\\{ {3;6;9;12} \\\right\\\}$
- $ B = \\\left\\\{ {0;3;6;9} \\\right\\\}$
- $ B = \\\left\\\{ {n \\\in N|0 \\\leqslant n \\\leqslant 9} \\\right.$ và $ \\\left. {n \\\vdots 3} \\\right\\\}$
- $ B = \\\left\\\{ {n \\\in N|0 < n \\\leqslant 9} \\\right.$ và $ \\\left. {n \\\vdots 3} \\\right\\\}$.