To write 2.40 in scientific notation, you express it as the product of a number between 1 and 10 and a power of 10.
In this case, 2.40 is already between 1 and 10, so you can write it as:
\[ 2.40 \times 10^0 \]
Thus, the scientific notation for 2.40 is \( 2.40 \times 10^0 \).