If a postage stamp indicates .250 or .169, what does this mean?

When a postage stamp indicates amounts like .250 or .169, it signifies that the postage is not sufficient for sending first-class mail. First-class mail typically has a minimum postage requirement which these amounts do not meet. The lowest rates for first-class mail currently exceed these values, making them inadequate for that class of service. Therefore, the stamps cannot be used for mailing any items that require first-class postage, essentially meaning they're not usable for sending standard letters or packages through first-class service.

Understanding the specific valuation of postage is crucial when determining its applicability, especially regarding different classes of mail. In this case, since the amount is notably lower than the standard first-class rate, it is clear that they would not be valid for this purpose.