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Which choice correctly expresses the number below in scientific notation?

0.0000000998

A. [tex]998 \cdot 10^{-8}[/tex]
B. [tex]99.8 \cdot 10^{-9}[/tex]
C. [tex]998 \cdot 10^{-10}[/tex]
D. [tex]9.98 \cdot 10^{-8}[/tex]
E. [tex]9.98 \cdot 10^{-9}[/tex]
F. [tex]9.98 \cdot 10^8[/tex]

Answer :

To express the number 0.0000000998 in scientific notation, follow these steps:

1. Identify the significant digits: Look at the number and find the first non-zero digit, which in this case is 9.

2. Rewrite the number: Move the decimal point right after this digit to rewrite the number as 9.98. This becomes the coefficient in scientific notation.

3. Count the decimal places moved: To get from the original number (0.0000000998) to 9.98, you have to move the decimal point 8 places to the right.

4. Determine the exponent: Because you moved the decimal point 8 places to the right, the exponent in scientific notation is -8. Negative exponents indicate that the original number was less than 1.

5. Combine into scientific notation: The scientific notation format is [tex]\(M \cdot 10^n\)[/tex], where [tex]\(M\)[/tex] is the number between 1 and 10, and [tex]\(n\)[/tex] is an integer. Based on our steps:
- The number (coefficient) is 9.98.
- The exponent is -8.

Therefore, the number 0.0000000998 expressed in scientific notation is [tex]\(9.98 \cdot 10^{-8}\)[/tex].

So, the correct choice is D. [tex]\(9.98 \cdot 10^{-8}\)[/tex].

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