Question

aratati ca diferenta abc-cba se divide la 9 si la 11

Answer 1

abc-cba=(100*a+10*b+c)-(100*c+10*b+a)=100*a+10*b+c-100*c-10*b-a=99*a-99*c=99*(a-c)=9*11*(a-c)  deci numarul se divide cu 9 si 11=99