Encoders and decoders are provided for memory systems. An encoder scrambles data bits corresponding to a logical page, selected from among multiple logical pages, using a plurality of random sequences, to generate a plurality of scrambled sequences; selects, as an encoded sequence, a scrambled sequence among the plurality of scrambled sequences; and provides a memory device with the encoded sequence to store the encoded sequence in multiple level cells. The selected scrambled sequence has the lowest number of logical high values among the plurality of scrambled sequences.