Items, for example grocery items in a shopping cart or warehoused items
being inventoried, are counted by electronically registering flickers
from tags attached to, or incorporated into, the items. The registration
takes place during an interval of time equal to the flicker repetition
rate of the tags. For example, each item's tag might flicker out an
identifying signal (preferably from an LED in the tag) in about a
thousandth of a second, and repeat this flicker once a second. A detector
registers all of the flickers from all of the items during a one-second
interval, and thereby counts the items because each will have flickered
once during that time. Other items, with different identifying flickers,
can be counted during the same interval. Thus, large numbers of various
tagged items can be counted rapidly.