What is 4 units left of zero
http://img.sparknotes.com/figures/5/50ca5e784bb7e4242910d5b8a571d103/number_line.gif
To determine what is 4 units to the left of zero, you need to understand the concept of a number line.
A number line is a straight line that represents every real number. It contains positive numbers to the right of zero and negative numbers to the left of zero. Zero itself is neither positive nor negative.
In this case, if zero is the starting point or reference point, moving "left" means going in the negative direction on the number line. Each unit represents a whole number increment or decrement. So, going four units to the left of zero means subtracting 4 from zero.
Mathematically, you can express this as:
0 - 4 = -4
Therefore, 4 units to the left of zero is -4.