Because I am not familiar with ternary four operations, I convert it into 10 before calculation.

(2 10 12 1 1)=2*3^6+ 1*3^5+ 1*3^3+2*3^2+ 1*3+ 1= 1750

Then convert 1750 to octal:

1750/8=2 18……6

2 18/8= 27…… 2

27/8 = 3…… 3

So the octal representation is 3326.