Question

aratati ca
11 bara langa ( ab + bc+ ca toate cu bara deasupra )

Answer 1

ab⇒scris in baza 10⇒ab=10a+b
bc⇒scris in baza 10⇒bc=10b+c
ca⇒scris in baza 10⇒ca=10c+a
ab+bc+ca=
10a+b+10b+c+10c+a=
11a+11b+11c=
11*(a+b+c)

Answer 2

11 divide pe ab+bc+ca , iar ab+bc+ca in baza 10= (10a+1b)+(10b+c)+(10c+a)= 11a+11b+11c => 11 | (11 a+ 11 b+ 11 c) .