standard_description: Recognize angle measure as additive. When an angle is decomposed into non-overlapping parts, the angle measure of the whole is the sum of the angle measures of the parts. Solve addition and subtraction problems to find unknown angles on a diagram in real world and mathematical problems, e.g., by using an equation with a symbol for the unknown angle measure.
problem_activity: Problem 1
a.   Solve.
6 × 3 = _____
60 × 3 = _____
60 × 30 = _____
b.   What do you notice about Part (a)? What do you wonder?
Problem 2
a.   Kristen and Rajiv are finding the product 80 × 50. Kristen says to find 8 × 50, then multiply by 10. Rajiv says to find 80 × 5, then multiply by 10.
Will both Kristen and Rajiv’s methods give the correct product? Why?
Write expressions to represent Kristen and Rajiv’s methods.
b.   Find the product 80 × 50.
Problem 3
Estimate the following products.
a.   41 × 32
b.   57 × 45
c.   24 × 77


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