First and second sets of numbers are received in an input range, which is separated into sub ranges. A first sub range is processed by initializing bits of a memory to a first logical state and by changing the initial state of each of the bits corresponding to a received number of the first set that is within the first sub range. Each number received in the second set is compared to a bit in the memory to identify a set of received numbers that are in the first sub range and that are in both the first set and the second set. The comparing is responsive to detecting a change of initial state of any bit in the memory during the processing of the first sub range. The processing and comparing is repeated for remaining sub ranges to identify received numbers that are in both the sets.