What is the numerical value of (2.1 × 10⁴)(4.0 × 10^-2)? A)8.4 B)8.4 × 10² C)8.4 × 10^-2 D)8.4 × 10^-8 E)none of the above

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Quizplus · Accepted Answer

When multiplying numbers in scientific notation, you multiply the coefficients (2.1 and 4.0 in this case) and add the exponents (11 + 1-2 = 10). Therefore, the numerical value is 8.4 × 10^10. However, we need to make sure this is in scientific notation, which requires the coefficient to be between 1 and 10. So we can rewrite 8.4 × 10^10 as 8.4 × 10^(10-12) = 8.4 × 10^-2, which is in scientific notation with the coefficient between 1 and 10. Therefore, the answer is B.

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