Answer:
70
Step-by-step explanation:
Apparently, you want the ratio of the weights:
(dino weight)/(car weight) = (2.8×10^5)/(4×10^3)
= (2.8/4)×10^(5-3) = 0.7×10^2 = 0.7×100
= 70
The heaviest dinosaur weighed about 70 times the weight of an average car.
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Your calculator can do arithmetic in scientific notation. So can any spreadsheet.
The applicable rule of exponents is ...
(10^a)/(10^b) = 10^(a-b)
