Question

Numerele de formă 123× divizibil cu 3 sunt ​

Answer 1

$1 + 2 + 3 + x\in\mathcal{M}_{3} \\ 1 + 2 + 3 + x\in\{3.6.9.12.15.18...\} \\ \implies \: \boxed{x \in\{0,3,6,9\}}$

$\\ \text{Numerele sunt: 1230,1233,1236,1239}$