We use a crypto data provider that is laser focused on high quality crypto currency data and reporting accurate and transparent pricing and metadata about the crypto currency market. Sometimes this means that some alt coins (for example, ones with a total supply in the quadrillions) aren't reported in the way you'd expect.
We know this will frustrate some users and we'll do our best to report results that make sense, but if you're seeing strange numbers for your favorite crypto currency please let us know and we'll look into it. For the most popular coins you can be confident that the data you're seeing is accurate and up to date.