Addition Facts

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 1: Addition Fact- A fact is an addition problem with two one-digit addends.
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 = (  7 9 8 )

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
Use 4 + 4 instead.
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 = (  7 8 6 )

(  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 = (  6 9 8 )

 

(  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 = (  13 9 11 )

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 = (  11 12 13 )

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

 

Addition Table*

+	1	2	3	4	5	6	7	8	9
1	2	3	4	5	6	7	8	9	10
2	3	4	5	6	7	8	9	10	11
3	4	5	6	7	8	9	10	11	12
4	5	6	7	8	9	10	11	12	13
5	6	7	8	9	10	11	12	14	15
6	7	8	9	10	11	12	13	14	15
7	8	9	10	11	12	13	14	15	16
8	9	10	11	12	13	14	15	16	17
9	10	11	12	13	14	15	16	17	18

 

*0 is not included because any number plus 0 is itself.
This table will help you find and memorize sums for addition facts. To use this table find the first addend on top and imagine a line going down from that number. Find the second addend on the left and imagine a line going right. The box where those two imaginary lines cross is the sum of those two numbers.
For example, for 5 + 7 go down from 5 and right from 7. They intersect at 12 so 5 + 7 = 12.

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