Answer
TRUE.
Work Step by Step
According to the definition of Scientific Notation given in the textbook, a number is written in scientific notation when it is expressed in the form $a \times 10^n$. $a$ can take any value between $-10$ and $10$, excluding $0$, while $n$ should be an integer and can take any integer value.
In the given case, $a=4$ and $n=3$. Therefore, both conditions are fulfilled.