Scientific notation has the form:



(4.4×10-19)(7.7×10-1)

Multiply the 4.4 by the 7.7 getting 33.88
Add the exponents of 10, (-19)+(-1) getting -20

That gives 

33.88×10-20

but that is not in scientific notation because
33.88 is not between 1 and 10.  So we write it 
in scientific notation as 3.388×101 and substitute
that for 33.88:

(3.388×101)×10-20

3.388×101×10-20

finally add the exponents of 10, (1)+(-20) getting -19 

3.388×10-19

Edwin