Add $1_3 + 12_3 + 212_3 + 2121_3.$ Express your answer in base 3.
Converting to base 10, we get 1 + 4 + 23 + 50. This is 79.
Converting back to base 3, 79 = 2221_3.
\(1_3 = 1\\12_3=1*3+2=5\\212_3=2*9+1*3+2=23\\2121_3 =2*27+1*9+2*3+1=70\)
