Grade
4

Guess My Rule: Number Pairs

A red circle and a blue circle overlap. Inside the red circle: 16 and 200, 25 and 128, 400 and 8, 160 and 20. Inside the blue circle: 3 and 6, 135 and 270, 16 and 32, 12 and 24, 255 and 510. Where the circles intersect: empty.
  1. Some number pairs belong in the circles, and some do not.
    What is the rule that decides what belongs in the red circle?
    What is the rule to decide what belongs in the blue circle?
    What is the rule to be in both circles?
  2. Can you write a number pair that would go inside the intersection of the circles? How do you know?
  3. Write another number pair that belongs in only the red circle.
  4. Write another number pair that belongs in only the blue circle.
  5. Write a number pair that would go outside of the circles. How do you know?
  • Try adding, subtracting, or multiplying the number pairs in the red circle. The answers to one of the operations will help you find the rule.
  • What do you notice about the number pairs in the blue circle?
  • Make your own rule, using numbers. You can use the circles below or draw your own.
  • If possible, show some examples that belong inside each circle and some examples that don’t belong in either circle.
outlines of overlapping red and blue circles, with space to write the rule for each circle
Printable Version

Google doc for printing and copying

Reference for Educators

Sample problems and solutions