Karl spent $58.34 at the grocery store last week. This week he spent $72.78. How much more did he spend this week than last week on groceries?
Karl spent $72.78 - $58.34 = $<<72.78-58.34=14.44>>14.44 more this week than last week on groceries. Answer: \boxed{14.44}.
To find out how much more Karl spent this week than last week on groceries, we need to subtract last week's spending from this week's spending.
This week's spending: $72.78
Last week's spending: $58.34
To calculate the difference, we subtract the last week's spending from this week's spending:
$72.78 - $58.34 = $14.44
Therefore, Karl spent $14.44 more this week on groceries than last week.