# Skills Handbook - Scientific Notation and Significant Digits - Exercises: 21

$$1.8\times 10^{-6}$$

#### Work Step by Step

In scientific notation, the number of significant digits is the number of digits in the leading number between $1$ and $10$. The final answer should have the same number of significant digits as the least number of significant digits in any of the numbers involved in the division: $4.9\times 10^{-8}$ has $2$ significant digits $2.7\times 10^{-2}$ has $2$ significant digits. Therefore, the final answer should be rounded to have $2$ significant digits. Rearrange factors and divide: $$\frac{4.9\times 10^{-8}}{2.7\times 10^{-2}}=\bigg(\frac{4.9}{2.7}\bigg)\bigg(\frac{10^{-8}}{10^{-2}}\bigg)=1.8\times 10^{-6}.$$

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