1. An encoder of a multiplier configured to multiply multiplier data with multiplicand data, the encoder comprising: an operator generating unit for encoding a plurality of received multiplier data to output a plurality of operators; and a partial-product data generating unit that generates a sign selecting operator from the received multiplier data for determining signs of the plurality of operators and for determining output paths for the multiplicand data, from one selection unit of the partial-product data generating unit to another selection unit of the partial-product data generating unit, prior to receiving the plurality of operators from the operator generating unit, and that outputs partial-product data in response to the received plurality of operators.