1. An apparatus for transforming digitized data, comprising: supplying means for supplying said digitized data; arithmetic means for executing operations on said supplied data for said transforming of the digitized data; said arithmetic means comprising bit-serial for performing bit-serial arithmetic operations; said bit-serial means comprising distributed strings of flip flops, adder and/or subtracter for performing said bit-serial arithmetic operations; said strings having a function of performing multiplications without any actual bit-parallel multiplier; and said multiplications using multiplication constants M1-MN by which said digitized data are multiplied, said multiplication constants M1-MN being integers and approximately in proportion to ideal-valued constants C1-CN such that M1/C1.apprxeq.M2/C2.apprxeq.. .. .apprxeq.MN/CN .apprxeq.P in which P is a non-two's power number.