Final answer:
To express the average age of Earth's crust, 2 × 10^7 years, as an integer, we convert it from scientific notation to standard form, resulting in 20,000,000 years.
Step-by-step explanation:
The average age of Earth's crust is estimated by scientists to be 2 × 10^7 years old, which is expressed in scientific notation. To express this number as an integer, we simply translate the scientific notation into standard form. This involves shifting the decimal point to the right seven places, as the exponent indicates the number of times we should multiply 10 by itself. Therefore, 2 × 10^7 years is equivalent to 20,000,000 years when expressed as an integer.
Understanding the transformations between scientific notation and standard form is a fundamental aspect of mathematics, especially when dealing with large numbers in topics like geology and earth sciences. These scientific fields often deal with vast time scales and distances, making scientific notation a critical tool for concise and precise communication. As such, our number, 20,000,000, helps us comprehend the immense span of time over which the earth's crust has been renewing itself.