[tex]4[/tex]
1) We need to find out a pattern for the powers that have a base 2:
[tex]\begin{gathered} 2^{1}=2 \\ 2^2=4 \\ 2^3=8 \\ 2^4=16 \\ 2^5=32 \\ 2^6=64 \\ 2^7=128 \\ 2^8=256 \\ (\ldots) \end{gathered}[/tex]
Note that from 4 to 4 powers the last digit starts to repeat itself.
2) So, let's proceed with this dividing the exponent 2058 by 4:
Now, note that the remainder is 2, therefore we can state that:
[tex]2^{2058}=same\: ones\: digit\: as\colon2^2=4[/tex]
