Fluent Addition and Subtraction with Near Doubles
Introduction
Near Doubles:
A near double is a math fact that is close to a double’s fact.
For example, 3+ 5 is considered a near double because it is close to the double’s fact 3+3.
- Near doubles could be doubles plus one fact, doubles plus two facts…
- We can use a doubles fact to find near-doubles facts.
Example:
Use a doubles fact to find near doubles facts.
3+ 4 =?
Solution:
We can use doubles fact to find the near doubles fact.
I can use the doubles fact 3 + 3.
3 + 4 = 3 + 3 + 1
6, and 1 more, is 7.
Problem-solving Using Near-double Facts:
Example 1:
Nela eats 2 apples. Anna eats 2 apples and then 2 more. How many apples do Nela and Anna eat in all?
Solution:
No. of apples Nela eats = 2
Anna eats 2 apples and then 2 more.
We can use doubles fact to find a near doubles fact.
2 + 4 =?
2 + 4 = 2 + 2 + 2 more.
4, and 2 more, is 6.
Nela and Anna ate 6 apples.
Example 2:
Tina has 3 books. Adam gave her another 4 books. How many books does Tina have now?
Solution:
No. of books with Tina = 3
Adam gave her another 4 books.
We can use doubles fact to find a near doubles fact.
3 + 4 =?
3 + 4 = 3 + 3 + 1 more.
6, and 1 more, is 7.
So, Tina has 7 books now.
Exercise
1. Use a double fact to find each near-doubles fact.
2. Use a double fact to find each near-doubles fact.
3 + 2 = ___________.
3. Write the missing numbers.
If 3 + _____ = 6, then 3 + _________ = 7.
4. Keyo finds 4 shells. Jack finds 5 shells. How many shells do they find in all?
___________ shells in all.
5. Use double facts to find each near-doubles fact.
2 + 4 = ______.
6. Use double facts to find each near-doubles fact.
7. Use double facts to find each near-doubles fact.
8. Use double facts to find each near-doubles fact.
9. How does know 2 + 2 help you find 2 + 3?
10. Jack eats 3 pears. Jane eats 3 pears and then 2 more. How many pears do Jack and Jane eat in all?
Concept Map:
What We Have Learned
- Use doubles facts to find near doubles facts.
- Solve the problems using near-double facts.
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