Answer
Find out the how many watts would it use if it is on for 8 days .
To prove
Let us assume that the watts would it use if it is on for 8 days be x .
As given
A computer uses 239 watts per hour.
As in one day there are 24 hours .
Than the equation becomes
x = 239 × 24 × 8
x = 45888 watts
Therefore 45888 watts of computer uses if it is on for 8 days .