A multiplication device is provided for forming the product of a first and a second N-bit input binary number. The multiplication device receives the two input binary numbers and forms a two's complement product expressed in a product sum and a product carry term. The product sum and product carry terms are formed by providing an offset generation means which generates a numerical binary offset of the value determined by X=(4-2.sup.-(n-1)) and a partial product generating means which generates first and second sets of partial products. An addition means adds the offset value and first and second sets of partial products are added to form the resultant product sum and product carry terms. The product sum and product carry terms are conveyed to a second addition means wherein they are added to form a two's complement product result. Preferably the multiplication device is provided with an accumulation means to form the sum of the products of all successive pairs of input binary numbers. In this manner, the second addition means also receives from a holding means an accumulation of previously formed products in two's complement form and adds the accumulation of products, the product sum and the product carry terms to form a new two's complement accumulation of products. The new accumulation of products is conveyed to the holding means where it replaces the old accumulation of products.