Open Middle®
Directions: Using the digits 0 to 9 at most one time each, place a digit in each box to make a true statement about these angles that add up to a straight angle. *Note: drawing not to scale.
Hint
What do you know about acute angles? How might the number of boxes for the addends tell us?
Answer
Ex: 42 + 138, 57 + 123, 48 + 132, many possible answers – consider having students have a more approximate angle measure after finding a solution
Source: Catherine Castillo
8 dime
20 penny
20 pennies 8 dime
100 penny + 40 dime + 4 penny
16 solutions:
23° + 157° = 180°
24° + 156° = 180°
26° + 154° = 180°
27° + 153° = 180°
32° + 148° = 180°
38° + 142° = 180°
42° + 138° = 180°
48° + 132° = 180°
53° + 127° = 180°
54° + 126° = 180°
56° + 124° = 180°
57° + 123° = 180°
72° + 108° = 180°
74° + 106° = 180°
76° + 104° = 180°
78° + 102° = 180°
121 plus 59 equals 180
23 degrees + 157 degrees = 180
78+102=180