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Quadrillion
Scale Variation
Understand that 'quadrillion' has different meanings in different countries, which might lead to confusion. 
Conceptualization
A quadrillion is abstract; it's hard to imagine such a big number in reality, but think of it as hyperbole. 
Scientific Usage
In science and math, 'quadrillion' is used precisely, but in everyday conversation, it often just means 'a lot'. 