Answer
$110_{two}$
Work Step by Step
Rightmost column:
$1+1=2=1\times 2+0\times 1=_{}10_{two}$
record the $0 $( carry the 1):
$.\qquad \ \ $1
$.\qquad \ \ $1$1_{two}$
$.\quad \ +\ $1$1_{two}$
$.\quad \_\_\_\_$
$.\qquad \ \ \ \ 0_{two} $
Next column:
$1+1+1=3_{ten}=1\times2+1\times1=11_{two}$
record the 1:
$.\qquad \ \ $1
$.\qquad \ \ $1$1_{two}$
$.\quad \ \ + $1$1_{two}$
$.\quad \_\_\_\_$
$.\qquad 110_{two} $
Check in base 10: 3+3=6
