binary long multiplication with decimal point
101.1 5.5d
x 1.01 1.25d
----------
110.111 6.825d
^
|
+---- Radix point is placed three places from the least significant bit.
The top factor has a radix point at one place from the right, and the
bottom factor has a radix point three places from the right.
1 place + 2 places = 3 places, so we insert a radix point at three places.