This application describes a method of multiplying numbers represented in multiple-word chains. The multiplication scheme allows for the multiplication of both signed and unsigned numbers of varying lengths. The multiplier block 30 executes a 17-bit by 17-bit two's complement multiply and multiply-accumulate in a single instruction cycle. A 4-bit shift value register with a 4 to 16 bit decoder 35 allows the multiplier to do a 1-16 bit barrel shift on either a 16-bit operand or an (N x 16)-bit chain operand.