Question

Subtract $3.2\times {10}^{-6}$ from $4.7\times {10}^{-4}$ with due regard to significant figures.

• A. $4.7\times {10}^{-4}$
• B. $7\times {10}^{-4}$
• C. $5.7\times {10}^{-4}$
• D. $4.7\times {10}^{-5}$

Answer 1

The correct option is A $4.7\times {10}^{-4}$

$4.7\times {10}^{-4}-3.2\times {10}^{-6}$

$=4.7\times {10}^{-4}-0.032\times {10}^{-4}$

$=4.668\times {10}^{-4}\approx 4.7\times {10}^{-4}$.