How does a signed number move us along a number line?

A signed number line uses zero as a reference point and places larger numbers to the right. A number's sign helps describe where it lies relative to zero. Adding a signed number is represented by a directed move from the starting location.

A positive addition moves right. A negative addition moves left. The size of the move is the added number's magnitude, meaning its distance from zero without its sign. Adding −3 therefore gives a three-unit move left, not a movement of negative length.

In the initial illustration, the start is −2 and the addition is +3. Moving right by three equally spaced units passes through −1 and 0 before reaching +1. The starting value is negative, but the endpoint is positive because the move crosses zero.

The direction of a move and the sign of its endpoint are different pieces of information. A positive addition does not always produce a positive answer; the result also depends on the start and the move's size. The drawing represents addition of integers on a mathematical line, rather than a physical journey or a rule for every operation with negative numbers.