To estimate the federal debt of country C at the end of fiscal year 2004, we can express the number in scientific notation.
The given amount is \( 278,560,125,000 \).
First, we can rewrite that in a simpler form:
- Identify the leading digit: The first digit is 2.
- Count the total number of digits after the first digit: There are 11 digits total (counting from the 2).
- To express this in scientific notation, we recognize that the number can be expressed as: \[ 2.78560125 \times 10^{11} \]
However, to provide an estimation, we can round \( 2.78560125 \) to \( 3 \) (the closest single digit).
Thus, the estimation becomes: \[ 3 \times 10^{11} \]
So, the closest estimation of the federal debt is: \[ 3 \times 10^{11} \]