The present invention relates to various digital watermarking methods, apparatus and systems. One claim recites a method of determining a size or denomination of a momentary object. The method includes: utilizing a configured, multi-purpose electronic processor, decoding a digital watermark embedded in a monetary object, the watermark including data corresponding to a denomination of the monetary object; based on the data, determining feedback to indicate the denomination of the monetary object; and providing the feedback. Handheld computing devices can be advantageously employed with this combination. Of course, other combinations are provided and claimed.