I'm confused about this example, isn't the count of grains of sand equal to the count of observable universes so it'd be a single grain of sand per universe?
The "about" does a lot of heavy lifting in this example. Dividing 10,000,000_10 by the number of grains that fit into one universe doesn't change it much. The 10,000,000 would get smaller somewhere in the deep depths of the decimal fraction.