Aplic formula:
(a + b)āæ = Mā + bāæ
Mā - inseamna multiplu de a.
Či proprietatea:
Mā ± Mā = Mā
8²ⶠ- 6³ⓠ= (7 + 1)²ⶠ- (7 - 1)³ⓠ=
= (7 + 1)²ⶠ- [7 + (-1)]³ā“
= (Mā + 1²ā¶) - [Mā + (-1)³ā“] =
= (Mā + 1) - (Mā + 1) =
= Mā + 1 - 1 =
= Mā
ā 8²ⶠ- 6³ⓠe divizibil cu 7.