Grade
5

Guess My Rule: Multiplication Madness

A red circle and a blue circle overlap. Inside the red circle: 57 times blank = 1,311. 91 times 11 = blank. 125 times 49 = 6,125. 37.53 times 100 = blank. Inside the blue circle: 499 times 2 = blank. 4 times 16 = blank. 24 times blank = 528. 2.5 times 12 = blank. Where the circles overlap: 4 times 1.25 equals blank. 13 times 31 = 403. 333 times 3 equals blank. Outside the circles: 167 times 6 = 1,002. 50 times 50 = 2,500.
  1. There are rules to decide what equations belong in the circles. Solve the equations to help find the rules. What is the rule to be in the red circle? What is the rule to be in the blue circle?
  2. What is the rule to be in the intersection of both circles?
  3. What is another expression that belongs in only the red circle?
  4. What is another expression that belongs in only the blue circle?

Start by finding the products of 91 × 11 in the red circle, 499 × 2 in the blue circle and 333 × 3 in the intersection of the circles. How are those products similar? How are they different?

Make your own rule involving multiplication. 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.

A red circle and a blue circle overlap. Each circle has a heading. The rule for the red circle is ... The rule for the blue circle is ...
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Reference for Educators

Sample problems and solutions