Apparatus for quickly sorting a succession of data words on the basis of the value of a specific parameter associated with each data word has a memory divided into M blocks of N storage locations each. A counting device includes a counter for each block, the content of each counter addressing the locations within the corresponding block. During a write operation an input data word and associated parameter are applied to an input, and the value of the parameter is used as a block address; prior to this happening the count in the counter associated with the relevant block is incremented by one. Also present is a priority determining device which, during a read operation, addresses, under the control of all counts in the counting device which indicate a number of data words other than zero in the relevant block, the block of highest priority thereamong, the locations in this block again being addressed by the corresponding counter. After the read operation, the count in the counter corresponding to the block read is decremented by one. If desired a predetermined fraction of the data words having, for example, the lowest parameter values can thus be detected.