Hey there!
This is a simple multiplication problem.
If she wants to download 14 movies that take up 500 meg each, we have to multiply 14 and 500 together to find the answer.
14 x 500
An easy way to do this is to multiply 14 x 5, then multiply that by 100.
This works because 5 x 100 = 500.
14 x 5 = 70
70 x 100 = 7,000
So, the 14 movies will need 7,000 meg of space.
Hope this helps!