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