Question

Add $3.8\times {10}^{-6}$ to $4.2\times {10}^{-5}$ with due regard to significant figures.

• A. $4.6\times {10}^{-5}$
• B. $4.6\times {10}^{-6}$
• C. $5.6\times {10}^{-6}$
• D. $6.6\times {10}^{-5}$

Answer 1

Answer: (A)

$4.6\times {10}^{-5}$

On adding we get

$3.8\times {10}^{-6}+42\times {10}^{-6}=45.8\times {10}^{-6}=4.58\times {10}^{-5}$

$=4.6\times {10}^{-5}$.

The given number in scientific notation for significant figure in order to produce the correct answer.