Three serial/parallel multipliers are introduced, which both receive the serial input data and produce the serial product in a most-significant-bit-first (MSB-first) fashion. Advantages of using MSB-first multiplication over conventional least-significant-bit-first multiplication include efficient calculation of MSB-first data from analogue/digital conversion; efficient interfacing with MSB-first algorithms such as square root and division; and simple truncation of the product. The approach does not utilise any special number system, but multiplier architectures both for unsigned and two's complement number representation (both for the direct and the Baugh-Wooley algorithms) are provided.