In the following we let K be the space of all infinitely differentiable test functions @ with compact support. If g is an infinitely differentiable function and @ is in K , then gQ, is in K and this leads to the following definition for the product fg = gf of a distribution f and an infinitely differentiable function g.Definition 1. Let f be a distribution and let g be an infinitely differentiable function. The product fg = gf is defined byFroin the definition of the derivative of a distribution we now have ((fg)', @) = -(fs, Q,') = -(f, g@? = -( A (9W' -g'@) = (1'9 + fg'9 @) and so f's = Us)' -fg'. More generally, it can be proved that r fWg = 2 rci(-1)d [fg(0](-4 i = O where r ! i!(r -i)!' = This leads us to the following definition for the product of two distributions, see [3]. Definition 2. Let f and g be two distributions for which on the open interval (a, b) f is the r-th derivative of an ordinary summable function F in LP(a, b) and g(r) is an ordinary summable function in LQ(a, b ) with -+ -= 1. Then the product fg = gf of g and f is defined on the interval (a, 6 ) by 1 1 P ! 7 r i = O f g = g f = c &(-l)i [ F g C i ) ] C 4 .