Method of operating memory device and memory controller for operatng memory device

The method of operating a memory device is disclosed. The memory device includes a plurality of multi-level memory cells containing the respective memory cells L level. The method of operating a memory device includes receiving the data expressed in Lee Jinsu; Generating a P- length string from the data; Converting the length of the string to P- Q- length string by estimating at least one level from the L level; And a step of programming the length of the Q- string to said plurality of memory cells.