140
A score is 20.
140u
A score is 20, so 4 score is 80.
A score is 20; so 21 X 20 = 420.
7
There are exactley 7 units of measurements
-7
No, they do not. They are pure numbers.
The SI has 7 base units. These units can be combined in an almost unlimited way to form other (derived) units. The Wikipedia article on "SI derived units" lists some examples.
7
4 - (-3) = 7