Theo đề bài ta có:
\(\overline{aaa}+\overline{bbb}+\overline{ccc}\) \(⋮\) 6;9;54
\(\Rightarrow\overline{aaa}+\overline{bbb}+\overline{ccc}\) \(⋮\) 54
\(\Rightarrow\) ( 100a + aa ) + ( 100b + bb ) + ( 100c + cc ) \(⋮\) 54
\(\Rightarrow\) ( 100a + 100b + 100c ) + ( aa + bb + cc ) \(⋮\) 54
\(\Rightarrow\) 100(a+b+c) + ( 10a + a + 10b + b + 10c + c ) \(⋮\) 54
\(\Rightarrow\) 100(a+b+c) + ( 10a + 10b + 10c ) + ( a + b + c ) \(⋮\) 54
Tự làm tiếp nhé
\(\overline{aaa}+\overline{bbb}+\overline{ccc}\\ =\left(111a\right)+\left(111b\right)+\left(111c\right)\\ =111\left(a+b+c\right)⋮6;9;54\\ \Rightarrow a+b+c⋮6;9;54\)
