: If the [[force]]s are in the same direction as each other, then they have a [[Positive (Number)|value]].
: If one [[force]] is acting in the opposite direction to another one of the [[force]]s is given a [[Negative (Number)|negative]] value.
{| class="wikitable"
|-
|[[File:ForceNumberLineVertical.png|center|200px]]
| style="height:20px; width:300px; text-align:center;" |If the 'up' direction is chosen to be [[Positive (Number)|positive]] then any [[vector]] pointing 'up' has a [[Positive (Number)|positive]] value and any [[vector]] pointing 'down' has a [[Negative (Number)|negative]] value.
In this [[diagram]] the green [[vector]] has a value of +2 while the red [[vector]] has a value of -4.
If the number lines represent the number of [[Newton]]s [[force]] then the [[Resultant Force]] is the two values added together.
F<sub>Resultant</sub> = (+2N) + (-4N)
F<sub>Resultant</sub> = -2N upwards
|}
{| class="wikitable"
|-
|[[File:ForceNumberLineHorizontal.png|center|400px]]
|-
| style="height:20px; width:400px; text-align:center;" |If the 'right' direction is chosen to be [[Positive (Number)|positive]] then any [[vector]] pointing 'right' has a [[Positive (Number)|positive]] value and any [[vector]] pointing 'left' has a [[Negative (Number)|negative]] value.
In this [[diagram]] the blue [[vector]] has a value of +3 while the yellow [[vector]] has a value of -2.
If the number lines represent the number of [[Newton]]s [[force]] then the [[Resultant Force]] is the two values added together.
F<sub>Resultant</sub> = (+3N) + (-2N)
F<sub>Resultant</sub> = 1N to the right
|}
{| class="wikitable"