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Mrs. Bulla |
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 MathChapter 3 - Subtraction
3-1 Fact Families
- Addition and subtraction are related and can be used to solve problems.
- In a fact family, there are three numbers that are used to create two addition and two subtraction problems.
4, 7, 11 8, 8, 16 9, 0, 9
4 + 7 = 11 8 + 8 = 16 9 + 0 = 9
7 + 4 = 11 16 - 8 = 8 0 + 9 = 9
11 - 7 = 4 9 - 0 = 9
11 - 4 = 11 9 - 9 = 0
3-2 Problem Solving
- Be sure to check if there is any information that is not needed.
- Use a 4-square organizer to solve the problem.
3-3 Mental Math
2 + 4 = 6 3 + f = 9 f = 6 x + 8 = 10 x = 2
20 + 40 = 60 30 + g = 90 g = 60 20 + 80 = y y = 100
200 + 400 = 600 300 + h = 900 h = 600 200 + z = 1,000 z = 800
3-4 Subtraction with Regrouping
- When subtracting with regrouping, it is important for the children to ask
the question, "Can I subtract these numbers?" If the answer is no, they
need to "regroup" by going to the next highest place and "TAKING" one
whole and "GIVING" to the original place.
3-6 Subtracting Across Zeros - When subtracting across zeros, it is important to ask the question, "Can I subtract these numbers?" Once that question is asked, you need to go next door to TAKE. If no one is home, go to the next place and TAKE. Then GIVE to the middle place. TAKE from the middle place, and GIVE to the ones. 3-7 Estimating - First, round to the highest place. Then, subtract like always! |
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