Question

$(1\times {10}^3)+(2\times {10}^2)+(3\times {10}^0)+(1\times {10}^{-1})+(2\times {10}^{-2})$=

• A. $123.12$
• B. $1230.12$
• C. $1230.21$
• D. $1230.21$

Answer 1

The correct option is D $1230.21$

Using $a^0=1$ and $a^{-m}=\frac{1}{a^m},$
$(1\times {10}^3)+(2\times {10}^2)+(3\times {10}^0)+(1\times {10}^{-1})+(2\times {10}^{-2})$
$=1000+200+3+\left(\frac{1}{10}\right)+\left(\frac{2}{100}\right)$
$=1000+200+3+0.1+0.02$
$=1203.12$