Doubles Near Doubles
Key Concepts
- Doubles Fact
- Near Doubles Fact
Introduction
Doubles
To get a double of a number, we add the same number to itself.
For example, double of 3 is 3 + 3 = 6.
Example 1:
Jenny has 4 marbles and she has bought 4 more new marbles. How many marbles does Jenny have?
Solution:
The double of 4 is 8.
Doubles fact
Example 2:
Find 5 + 5.
Solution:
Let’s take some cubes to solve this.
Doubles fact: 5 + 5 = 10
Example 3:
Find 9 + 9.
Solution:
Let’s take some cubes to solve this.
Doubles fact: 9 + 9 = 18
Near doubles fact
When adding numbers that follow each other, use the knowledge of doubles to help add the numbers.
3 + 4 is same as 3 + 3 + 1 = 7
Example 4:
Find 4 + 5.
Solution:
Double fact: 4 + 4 = 8
4 + 5 is one more than 4 + 4.
Near Doubles fact: 4 + 5 = 9
Example 5:
Find 10 + 8.
Solution:
Double fact: 8 + 8 = 16
10 + 8 is two more than 8 + 8.
Near Doubles fact: 10+ 8 = 18
Exercise
- Complete the doubles fact. Use cubes if needed.
8 + 8 = ______ - Choose all the pictures that represent a double.
- Complete the doubles fact. Use cubes if needed.
2 + 2 = ______ - Complete the doubles fact. Use cubes if needed.
5 + 5 = ______ - Complete the doubles fact. Use cubes if needed.
10 +10 = ______ - Use the doubles facts and solve the near doubles. Use cubes if
needed.
3 + 2 = ______ - Use the doubles facts and solve the near doubles. Use cubes if
needed.
5 + 6 = ______ - Use the doubles facts and solve the near doubles. Use cubes if
needed.
Concept Map
What have we learned
- Use Doubles fact and add two numbers that are the same.
- Use Near Doubles fact and add two numbers that follow each other.
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