Doubles facts: Addition problems where the same number is added to itself
Note: Doubles facts are foundational for mental math and help with other addition strategies.
- Recognize that we're adding the same number twice
- Count the number of groups: 2 groups of 5
- Multiply: 2 × 5 = 10
We're adding 5 twice: 5 + 5
2 groups of 5 objects: ⭐⭐⭐⭐⭐ and ⭐⭐⭐⭐⭐
Total: 5 + 5 = 10 objects
5 + 5 = 10
• Doubles: Same number added to itself
• Pattern: Doubles always result in even numbers
• Memory tip: Practice doubles facts until automatic
- 4 + 4 = 8 - Practice with smaller doubles
- 6 + 6 = 12 - Practice with medium doubles
- 3 + 3 = 6 - Practice with single digits
- Doubles always result in even numbers
- Memorize doubles facts for mental math speed
- Use doubles to help with near doubles
Q: Why are doubles facts important?
A: They build fluency and help with other addition strategies like near doubles.
Q: What numbers can be doubled?
A: Any number can be doubled, but we focus on 1-10 for early grades.
Near doubles: Addition problems where the numbers are consecutive (differ by 1)
Note: Near doubles can be solved using known doubles facts plus or minus 1.
- Recognize that 5 and 6 are consecutive numbers
- Use the closest doubles fact: 5 + 5 = 10
- Add 1 more since 6 is 1 more than 5
5 and 6 are consecutive numbers (differ by 1)
We know 5 + 5 = 10
Since 6 is 1 more than 5, add 1 to the doubles result: 10 + 1 = 11
5 + 6 = 11
• Near doubles: Consecutive numbers can use doubles strategy
• Strategy: Use closest doubles fact and adjust
• Memory tip: Near doubles are doubles ± 1
- 4 + 5: Use 4 + 4 = 8, then 8 + 1 = 9
- 6 + 7: Use 6 + 6 = 12, then 12 + 1 = 13
- 3 + 4: Use 3 + 3 = 6, then 6 + 1 = 7
- Near doubles are one number apart
- Use the smaller number for the doubles fact
- Add 1 more than the doubles result
Q: What are near doubles?
A: Addition problems with consecutive numbers like 4+5 or 7+8.
Q: How do I solve near doubles?
A: Use the doubles fact for the smaller number and add 1.
Doubles plus one: Addition problems where one number is 1 more than the other
Note: This is a specific type of near doubles where one number is exactly 1 more than the other.
- Recognize that 5 is 1 more than 4
- Use the doubles fact: 4 + 4 = 8
- Add 1 more: 8 + 1 = 9
5 is exactly 1 more than 4
We know 4 + 4 = 8
Since 5 is 1 more than 4, add 1 to the doubles result: 8 + 1 = 9
4 + 5 = 9
• Doubles plus one: One number is exactly 1 more than the other
• Strategy: Use doubles fact and add 1
• Memory tip: This is the same as near doubles
- 3 + 4: Use 3 + 3 = 6, then 6 + 1 = 7
- 6 + 7: Use 6 + 6 = 12, then 12 + 1 = 13
- 2 + 3: Use 2 + 2 = 4, then 4 + 1 = 5
- Look for numbers that are 1 apart
- Always use the smaller number for the doubles fact
- Add 1 to the doubles result
Q: What is doubles plus one?
A: Addition problems where one number is 1 more than the other, like 4+5 or 7+8.
Q: How is this different from regular near doubles?
A: Doubles plus one is a specific case of near doubles where the difference is exactly 1.
Doubles plus two: Addition problems where one number is 2 more than the other
Note: This strategy uses the doubles fact and adds 2 more to the result.
- Recognize that 6 is 2 more than 4
- Use the doubles fact: 4 + 4 = 8
- Add 2 more: 8 + 2 = 10
6 is exactly 2 more than 4
We know 4 + 4 = 8
Since 6 is 2 more than 4, add 2 to the doubles result: 8 + 2 = 10
4 + 6 = 10
• Doubles plus two: One number is exactly 2 more than the other
• Strategy: Use doubles fact and add 2
• Memory tip: This builds on doubles knowledge
- 3 + 5: Use 3 + 3 = 6, then 6 + 2 = 8
- 5 + 7: Use 5 + 5 = 10, then 10 + 2 = 12
- 2 + 4: Use 2 + 2 = 4, then 4 + 2 = 6
- Look for numbers that are 2 apart
- Always use the smaller number for the doubles fact
- Add 2 to the doubles result
Q: What is doubles plus two?
A: Addition problems where one number is 2 more than the other, like 4+6 or 5+7.
Q: How do I solve doubles plus two?
A: Use the doubles fact for the smaller number and add 2.
Triple addition: Adding the same number three times
Note: This builds on doubles knowledge and prepares for multiplication.
- Recognize that we're adding 3 three times
- Group the addition: (3 + 3) + 3
- Solve the doubles first: 3 + 3 = 6
- Add the third number: 6 + 3 = 9
We're adding 3 three times
First, add two of the threes: 3 + 3 = 6
Add the result to the third 3: 6 + 3 = 9
3 + 3 + 3 = 3 × 3 = 9
3 + 3 + 3 = 9
• Triple addition: Adding the same number three times
• Strategy: Group into doubles first, then add the third
• Connection: This relates to multiplication (3 × 3 = 9)
• Memory tip: Practice triples as doubles plus the number again
- 2 + 2 + 2: Use 2 + 2 = 4, then 4 + 2 = 6
- 4 + 4 + 4: Use 4 + 4 = 8, then 8 + 4 = 12
- 5 + 5 + 5: Use 5 + 5 = 10, then 10 + 5 = 15
- First add two of the numbers using doubles
- Then add the third number to the doubles result
- This connects to multiplication concepts
Q: What is triple addition?
A: Adding the same number three times, like 3+3+3 or 4+4+4.
Q: How do I solve triple addition?
A: Add two of the numbers first using doubles, then add the third.