Question

Aflati toate numerele naturale care impartite la  7 dau catul  egal cu restul.

Answer 1

a=7c+r    r < 7   ⇒   r∈{0,1,2,3,4,5,6}       a = 7r+r       a=8r               a∈{0,8,16,24,32,40,48}