Question

Simplify the following expression using scientific notation:
$1.24\times {10}^5+4.7\times {10}^3$

• A. $5.94\times {10}^5$
• B. $2.71\times {10}^5$
• C. $1.287\times {10}^5$
• D. $1.287\times {10}^3$

Answer 1

The correct option is C $1.287\times {10}^5$

$\underset{–}{\text{Need to simplify:}}$ $1.24\times {10}^5+4.7\times {10}^3$

First, we need to make both the exponents of $10$ same, and then we can add.

In $4.7\times {10}^3,$ moving the decimal point $2$ places to the left which results in $0.047\times {10}^2\times {10}^3=0.047\times {10}^5.$

Substituting $0.047\times {10}^5,$ we get

$1.24\times {10}^5+4.7\times {10}^3$
$=1.24\times {10}^5+0.047\times {10}^5$
$=(1.24+0.047)\times {10}^5$
$=1.287\times {10}^5$

Hence, the value of the expression $1.24\times {10}^5+4.7\times {10}^3$ is $\underset{–}{1.287\times {10}^5}$.

$\therefore$ Option (c.) is the correct one.