The answer is -6300
Explanation:
6.3 x 10^-3
1) Accoring to PEMDAS, we must do 10^-3 first. 10 x 10 x 10 = 1,000, then we add the negative
6.3 x -1000
2) Now we just move the decimal on 6.3 three times to the right, then add the negative
6.3 x -1000
-6300