This is nerd-speak for "my guess was way, way off": the database under consideration would have to not just double in size, not just be 10x larger, but be 100x,

This is nerd-speak for "my guess was way, way off": the database under consideration would have to not just double in size, not just be 10x larger, but be 100x, maybe even 1000x or 10,000x bigger before it stopped fitting in memory. And her time at Google had her used to dealing pretty much exclusively with datasets at several hundreds of thousands times larger than the one this job was asking her to think about. "Orders of magnitude" are a concept found wherever you have to deal with absurdly large or absurdly tiny numbers; if you've ever seen someone write a number like "2 x 10^9" then you're seeing someone use a little of this - they're saying "about two billion". Wikipedia's page on the subject of orders of magnitude might be a decent introduction to the concept: https://en.wikipedia.org/wiki/Order_of_magnitude https://en.wikipedia.org/wiki/Order_of_magnitude