The numbers on a horizontal number line are oriented from right to left.
The numbers on a vertical number line are oriented from top to bottom.
The numbers on a horizontal number line are oriented from left to right.
The numbers on a vertical number line are oriented from right to left.
"oriented" here tells us in which direction numbers are increasing. Convention has it that in rectangular coordinates, x increases from left to right and y increases as you progress upward parallel to the y-axis.
