A method of operating a nonvolatile memory device comprises defining a bit ordering for a plurality of n-bit (n>2) multi-level cells such that bit-reading numbers associated with different pages of the n-bit multi-level cells are substantially equalized, wherein the bit ordering assigns at least one bit “0” to an erased state of the n-bit multi-level cells, and programming n-bit data into each of the n-bit multi-level cells according to the bit ordering.