To find out how much flour Aiden has left after making biscuits, you can subtract the amount of flour used from the total amount of flour he initially had.
Starting amount of flour: 8.1 ounces
Amount of flour used: 7.76 ounces
Now, subtract the amount used from the starting amount:
\[ 8.1 - 7.76 = 0.34 \]
Aiden has 0.34 ounces of flour left.