Understanding Distance & Coordinates

Subtraction as Distance

Formative Assessment

Summary of the Math: Subtraction as Distance

Read and Discuss

Subtraction can be looked at as the distance between two numbers.

You can use the number line to model the subtraction ab as distance, where a and b are any two numbers (positive or negative), as follows.

  • Locate points a and b.
  • Find the distance between points a and b. This value will be a positive number, because a distance is always positive.
  • Determine the sign of the distance value in order to find the answer to the subtraction problem. The value of a − b is:
    • Positive if a > b (if a is to the right of b on the number line).
    • Negative if a < b (if a is to the left of b on the number line).

Hint:

Can you:

  • Explain the method for subtracting integers by finding the distance between two points on a number line?