Question

Which of the following expression is equivalent to $2.45\times {10}^6$ sq ft?

• A. $0.075\times {10}^7+170\times {10}^5$
• B. $0.075\times {10}^6+170\times {10}^4$
• C. $0.075\times {10}^7+170\times {10}^4$
• D. $0.075\times {10}^6+170\times {10}^6$

Answer 1

The correct option is C $0.075\times {10}^7+170\times {10}^4$

Let us look at the third option
Given: $0.075\times {10}^7+170\times {10}^4$

Convert the numbers to have equal exponents and then add,
$0.75\times {10}^7\times {10}^{-1}+1.70\times {10}^4\times {10}^2$
$=0.75\times {10}^{7-1}+1.70\times {10}^{4+2}$
$=0.75\times {10}^6+1.70\times {10}^6$
$=(0.75+1.70)\times {10}^6$
$=2.25\times {10}^6$