Question

1)determinati toate numerele naturale de 2 cifre care impartite printr-un numar de o cifra dau restul 7

Answer 1

restul< impartitorul ⇒ impartitorul={8,9}
10≤8×n+7≤99  ⇒ {15,23,31,39,47,55,63,71,79,87,95}
10≤9×n+7≤99  ⇒{16,25,34,43,52,61,70,79,88,97}