Memory devices and multi-bit programming methods are provided. A memory device may include a plurality of memory units; a data separator that separates data into a plurality of groups; a selector that rotates each of the plurality of groups and transmits each of the groups to at least one of the plurality of memory units. The plurality of memory units may include page buffers that may program the transmitted group in a plurality of multi-bit cell arrays using a different order of a page programming operation. Through this, evenly reliable data pages may be generated.