Pentru orice a ∈ R {\displaystyle a\in \mathbb {R} } se defineşte a 0 := 1 , {\displaystyle a^{0}:=1,} dacă a ≠ 0 ; a 1 = a ; a n + 1 = a ⋅ a n ( ∀ ) n ∈ N . {\displaystyle a\neq 0;\;a^{1}=a;\;a^{n+1}=a\cdot a^{n}\;(\forall )n\in \mathbb {N} .}
Evident, 0 n = 0 {\displaystyle 0^{n}=0} şi 1 n = 1 ( ∀ ) n ∈ N . {\displaystyle 1^{n}=1\;(\forall )n\in \mathbb {N} .}