-5 x -4 ÷ -2 = ?
At this point, numbers stop being used to count quantity.
Instead they count distance, and usually distance from a start point.
You'd be right to question how that start point came into being, and how its held there.
Water level is a good start point. It's held there by gravity and sorted according to the relative density of air to water.
E.g.
You can be at water level, 0
Fly above it. +1
Sink below it. -1
Thus we introduce the idea of direction.
-5 x -4 ÷ -2 = ?
taking the first part the
-5 x -4 = 20
the simplified equation is now
20 ÷ -2 = ?
20 ÷ -2= -10
The answer is -10 units.
(Ten units away from the zero point, but under the water's surface rather than flying above it.)
* It's interesting to note, that zero has now changed meaning, going from meaning "empty" to meaning "at balance or equilibrium"
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