Answer:
Hello,
Step-by-step explanation:
unit mean the unit digit of ...
[tex]unit(7^0)=unit(1)=1\\unit(7^1)=unit(7)=7\\unit(7^2)=unit(49)=9\\unit(7^3)=unit(7^2)*7=unit(9*7)=unit(63)=3\\unit(7^4)=unit(7^3)*7=unit(3*7)=1\ just\ like\ unit(7^0)\\[/tex]
[tex]\left \{ \begin {array}{cc}1&if\ n \in 4*\mathbb{N}\\7&if\ n \in 4*\mathbb{N}+1\\9&if\ n \in 4*\mathbb{N}+2\\3&if\ n \in 4*\mathbb{N}+3\\\end {array} \right.\\\\\\unit(7^{7^{7}})=unit(7^{(7^{7})})=unit(7^{823543})=unit(7^3)=3\\\\unit((7^{7})^{7}) =unit(7^{49} )=unit(7^{1})=7\\[/tex]
I have given 2 answers since i don't know what you mean with 7^7⁷.
