Question

Mark the correct alternative in each of the following:

3 × 0.3 × 0.03 × 0.003 × 30 =

(a) 0.0000243 (b) 0.000243 (c) 0.00243 (d) 0.243

Answer 1

$$\begin{gathered} 3\times 0.3\times 0.03\times 0.003\times 30 \\ =3\times \frac{3}{10}\times \frac{3}{100}\times \frac{3}{1000}\times 3\times 10 \\ =\frac{3\times 3\times 3\times 3\times 3}{100\times 1000} \\ =\frac{243}{100000} \\ =0.00243\left(\mathrm{Decimal}\mathrm{point}\mathrm{is}\mathrm{shifted}\mathrm{to}\mathrm{left}\mathrm{by}5\mathrm{places}\right) \end{gathered}$$

Hence, the correct answer is option (c).