[tex]\left(3.5\times 10^{-2}\dfrac{kg}{L}\right)\times\left(2.64\times 10^{20}\,L\right)=(3.5\times 2.64)\times 10^{(-2+20)}\,kg\\\\=\bf{9.24\times 10^{18}\,kg}[/tex]
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Multiply the numbers and add the exponents.
