Answer
1101
Work Step by Step
Align the numbers at the decimal point and subtract the digits with the same place value.
In binary notation, the allowable digits are 0 and 1. In standard Base 10 notation, when the subtrahend is greater than the minuend you "borrow" from the column to the left. You add 10 to the minuend you are working and subtract 1 from the minuend to the left.
In binary(or Base 2) subtraction, the same process is used. 2, written as $10_2$ is borrowed from the column to the left.
$\ \ \ /\!\!\!1\overset{10}/\!\!\!1\overset{10}01\,1$
$\underline{\ \ \ \ \ 1\,1\,1\,0}$
$\ \ \ \ \ 1\,1\,0\,1$
