To express the amount \( 15,528.23 \) in the form of \( a \times 10^n \), we first need to find \( a \) (a single digit) and \( n \) (the exponent).
We can rewrite \( 15,528.23 \) as follows:
\[ 15,528.23 = 1.552823 \times 10^4 \]
Here, \( a = 1.552823 \) which has more than one digit. To express \( 15,528.23 \) as a single digit, we can round \( 1.552823 \) to a single digit, specifically rounding to the nearest tenths place which gives us \( 1.6 \).
Thus, adjusting \( n \) accordingly:
\[ 15,528.23 \approx 1.6 \times 10^4 \]
So the amount \( 15,528.23 \) expressed in the form of \( a \times 10^n \) where \( a \) is a single digit is:
\[ \boxed{1.6 \times 10^4} \]