Which of the following numbers is written in scientific notation?

• A. 0.00032
• B. 3.2 × 10^5
• C. 32 × 10000
• D. 320000

Answer: (B)

Verified step by step guidance

1. Understand the definition of scientific notation: a number is written in scientific notation if it is expressed as \(a \times 10^{n}\), where \$1 \leq |a| < 10\( and \)n$ is an integer.
2. Examine each option to see if it fits the form \(a \times 10^{n}\) with \(a\) between 1 and 10.
3. For the number \$0.00032\(, rewrite it as \)3.2 \times 10^{-4}\(, which fits scientific notation because \)3.2$ is between 1 and 10.
4. For the number \$3.2 \times 10^{5}\(, check that \)3.2$ is between 1 and 10 and the exponent is an integer, so this is in proper scientific notation.
5. For the numbers \$32 \times 10000\( and \)320000\(, note that they are not written in the form \)a \times 10^{n}\( with \)a$ between 1 and 10, so they are not in scientific notation.