`\color{#B9D3EE}{\text{#}}\color{#9FB6CD}{\text{Y}}\color{#6C7B8D}{\text{u}}\color{#696969}{text{u}}\color{#828282}{\text{k}}\color{#b5b5b5}{\text{a}\color{#B9D3EE}{\text{i}}\color{#9C9C9C}`

`-` Ta có :

`40 = 2^3 . 5`

`⇒` `(1+1) . (1+1) . (1+1) = 8` `(` ước `)`.

`66 = 2 . 3 . 11`

`⇒` `(1+1) . (1+1) . (1+1) = 8` `(` ước `)`.

`78 = 2 . 3 . 13`

`⇒` `(1+1) . (1+1) . (1+1) = 8` `(` ước `)`.

`120 = 2^3 . 3 . 5`

`⇒` `(3+1) . (1+1) . (1+1) = 16` `(` ước `)`.

`196 = 2^2 . 7^2`

`⇒` `(2+1) . (2+1) = 9` `(` ước `)`.