This is such a basic question I'm sure, but I've been trying to find a robust solution to it for a while.
Lets say I have the numbers 0-100 in series.
As the number increases, I want another number say 1000, to decrease. so that when you got to 100, it was at 0
0 = 1000
50 = 500
100 = 0
What is this kind of series called?