Question

Express 0.0000987 in standard form.

• A. $9.87\times {10}^5$
• B. $98.7\times {10}^6$
• C. $9.87\times {10}^{-5}$
• D. $98.7\times {10}^{-6}$

Answer 1

The correct option is C $9.87\times {10}^{-5}$

Any number can be expressed as a decimal number between 1.0 and 10.0 including 1.0 multiplied by a power of 10. Such a form of a number is called its standard form.
$0.0000987=\frac{987}{10000000}$
$=\frac{9.87\times {10}^2}{{10}^7}$
$=9.87\times {10}^{2-7}(\because \frac{a^m}{a^n}=a^{m-n})$
$=9.87\times {10}^{-5}$
$\therefore$ The standard form of 0.0000987 is $9.87\times {10}^{-5}$