Addition facts are all the addition combinations of 1-digit numbers (including 0)
The following are all examples of addition facts: 7 + 2, 9 + 0, 7 + 9, and 0 + 6.
Reminder 2: [3 + 5 = 8] In this case the 3 and 5 are called addends. The 8 is the sum.
Reminder 3: Commutative Property of Addition - Changing the order of the addends does not change the sum. 3 + 5 = 5 + 3
Reminder 4: Associative Property- Changing the way that the addends are grouped does not change the sum. [3 + 5] + 4 = 3 + [5 + 4]

Facts With Sums of 10 or Less

Here are a few short methods to help memorize facts with sums of ten or less.

Method 1: If the second addend in an addition problem is greater than the first, the problem can be made easier by switching the addends using the commutative property.  This way it is simpler to count up from the first number to get the sum.
Example: 3 + 7 If you don’t remember, switch the numbers. 7 + 3 is easier.
If you still don’t remember, count up from 7. 7, 8, 9, 10. 10 is the sum.
Practice this method with these problems.
Practice 1:
2 + 6
6 + 2 = (  )

Correct
Wrong

Practice 2:
4 + 5

 5 + (  6 4 3 ) = (  7 9 10 ) Correct Wrong Correct Wrong

Method 2: If you have two addends that are near doubles, or numbers with a difference of 1 (for example 3 and 4), then it is easy to double the lower number and add one to it.
Example: 4 + 5
4 + 4 = 8
8 + 1 = 9 because 4 +5 is 1 more than 4 + 4.

Method 3: Sometimes, it is a good idea to split one addend into smaller numbers that add up to that addend, and then add them, one at a time, to the first number.

Example: 5 + 4
Split the 4 into 3 + 1
5 + 4 = 5 + [3 + 1] = [5 + 3] + 1 = 8 + 1 = 9
You can also split the 4 into 2 + 2, since 2 + 2 also adds up to 4.
5 + 4 = 5 + [2 + 2] = [5+2] + 2 = 9
This is the associative property.

Practice this method with the problem 6 + 3
Split the 3 into 2 + 1 then add.
6 + 2 = (  )

Correct
Wrong
 (  6 8 9 )   + 1 = (  8 9 11 ) Correct Wrong Correct Wrong

Practice 2:
7 + 3

 7 + (  1 4 5    + 0 5 2 ) Correct Wrong Correct Wrong

7 + 1 = (  )

Correct
Wrong

 (  10 8 9 )   + 2 = (  11 9 10 ) Correct Wrong Correct Wrong

Solve Mentally (using any method)
1. 3 + 5
2. 4 + 3
3. 3 + 6
4. 8 + 2
5. 6 + 4
6. 7 + 2

Facts with Sums Greater than 10

Method 1: If the second addend in an addition problem is greater than the first, the problem can be made easier by switching the addends using the commutative property. This is very much like the first method for adding with sums of ten or less.
Example: 4 + 8 Switch the numbers to get 8 + 4.
8 + 4 = 12, so 4 + 8 is also 12

Practice these problems using Method 1;
Practice 1:
2 + 9
9 + 2 = (  )

Correct
Wrong

Practice 2:
5 + 7

 (  8 7 9 ) + (  4 6 5 ) = (  14 12 11 ) Correct Wrong Correct Wrong Correct Wrong

Method 2: If you have two addends that are near doubles, or numbers with a difference of 1 (for example 7 and 8), then it is easy to double the lower number and add one to it. This is like method 2 of addition with sums of ten or less.
7 +8 is 1 more than 7 + 7.
7 + 8 = 7 + 7 + 1 = 14 + 1 = 15
So, 7 + 8 = 15

Practice these problems using Method 2;
Practice 1:
7 + 6
6 + 6 + 1 = (  )

Correct
Wrong

Practice 2:
8 + 9

 8 + (  10 8 9 ) + (  4 2 1 ) = (  16 17 18 ) Correct Wrong Correct Wrong Correct Wrong

Method 3: Split the smaller addend into two parts so that the first part adds up with the biggest addend to make ten. Then add on the second part.
Example: 9 + 5
9 + 1 = 10 Since you took 1 from 5 that leaves 4. [1 + 4 = 5]
10 + 4 = 14
So, 9 + 5 = 14.

Practice this method using these problems;
Practice 1:
8 + 5

 8 + (  1 2 3 ) = 10 Correct Wrong

 5 = (  4 1 2 )   + (  5 0 3 ) Correct Wrong Correct Wrong

 10 + (  1 3 4 ) = (  11 14 13 ) Correct Wrong Correct Wrong

Practice 2:
9 + 4

 9 + (  2 3 1 ) = (  14 10 13 ) Correct Wrong Correct Wrong

 4 = (  6 5 1 )   + (  2 0 3 ) Correct Wrong Correct Wrong

 (  8 10 9 ) + (  4 2 3 ) = (  12 13 11 ) Correct Wrong Correct Wrong Correct Wrong

Solve Mentally (using any method):
1. 7 + 8
2. 7 + 6
3. 2 + 9
4. 9 + 3
5. 8 + 6
6. 5 + 7