I'm not great at direct addition, so let's convert everything to base 10. We have
\((221)_3 = (2 × 3^2) + (2 × 3^1) + (1 × 3^0) = (25)_{10} \)
\((122)_3 = (1 × 3^2) + (2 × 3^1) + (2 × 3^0) = (17)_{10} \)
Adding these two numbers up, we get \(25+17=42\)
So now we want to convert 42 back to base 3.
First, we do 42/3, which has a quotient of 14 and remainder of 0.
Next, we take 14 and have 14/3, which has a quotient of 4 and remainder of 2.
Next, we do 4/3, which has a quotient of 1 and remainder 1.
Lastly, we do 1/3, which has quotient 0 and remainder 1.
So our number is \(42_{10}=1120_3\)
Our final answer is \(1120_3\)
Thanks! :)