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Addition and Subtraction Strategies Reference
 Counting On/Counting Back- Counting is a simple strategy to use when adding or subtracting 1,
2, or 3. Start with the greater number and add or subtract 1, 2, or 3.
3 + 12 = 15
Start at 12; count up 13, 14, 15
1+8=9
Start at 8, count up 1 to 9.
15 – 3 = 12
Start at 15; count down 14, 13, 12
9–1=8
Start at 9, count down 1 to 8.
 Doubles: Doubles are facts in which an addend is added to itself. When solving subtraction
problems with doubles think addition.
1+1=2
6+ 6 = 12
2–1=1
12 – 6 = 6
2+ 2 = 4
7 + 7 = 14
4–2=2
14 – 7 = 7
3+3=6
8 + 8 = 16
6–3=3
16 – 8 = 8
4+4=8
9 +9 = 18
8–4=4
18 – 9 = 9
5 + 5 = 10
10 + 10 = 20
10 – 5 = 5
 Doubles +1: Double the smaller number and then add 1
3+4=7
Think 3 + 3 + 1 = 7
7 + 8 = 15
Think
7 + 7 + 1 = 15
4+5=9
Think 4 + 4 + 1 = 9
8 + 9 = 17
Think
8 + 8 + 1 = 17
5 + 6 = 11
Think 5 + 5 + 1 = 11
9 + 10 = 19
Think
9 + 9 + 1 = 19
6 +7 = 13
Think 6 + 6 + 1 = 13
 Doubles – 1: Double the larger number and then subtract 1
4+3=7
Think 4 + 4 - 1 = 7
8 + 7 = 15
Think
8 +8 - 1 = 15
5 +4 = 9
Think 5 +5 - 1 = 9
9 +8 = 17
Think
9 + 9 - 1 = 17
6 +5 = 11
Think 6 +6 - 1 = 11
10 + 9 = 19
Think
10 +10 - 1 = 19
7 +6 = 13
Think 7 +7 - 1 = 13
20 – 10 = 10
 Doubles + 2 (Inside Doubles): Inside doubles are when two addends are part of a three number
sequence (5, 6, and 7). Look for the number that falls between the two numbers and double it
to find the answer. Or double the smaller number and add 2.
Equations
Inside Doubles
Doubles + 2
(Double the number in between)
(Double the smaller number and add 2)
1+3=4
3+1=4
Think
2+2=4
Think 1 + 1 + 2 = 4
2+4=6
4+2=6
Think
3+3=6
Think 2 + 2 + 2 = 6
3+5=8
5+3=8
Think
4+4=8
Think 3 + 3 + 2 = 8
4 + 6 = 10
6 + 4 = 10
Think
5 + 5 = 10
Think 4 + 4 + 2 = 10
5 + 7 = 12
7 + 5 = 12
Think 6 + 6 = 12
Think 5 + 5 + 2 = 12
6 + 8 = 14
8 + 6 = 14
Think 7 + 7 = 14
Think 6 + 6 + 2 = 14
7 + 9 = 16
9 + 7 = 16
Think 8 + 8 = 16
Think 7 + 7 + 2 = 16
MAKE A TEN
 Tens Partners: Recognizing what numbers when combined make a ten
0 + 10 = 10
10 – 0 = 10
5 + 5 = 10
10 – 5 = 5
1 + 9 = 10
10 – 1 = 9
6 + 4 = 10
10 – 6 = 4
2 + 8 = 10
10 – 2 = 8
7 + 3 = 10
10 – 7 = 3
3 + 7 = 10
10 – 3 = 7
8 + 2 = 10
10 – 8 = 2
4 + 6 = 10
10 – 4 = 6
9 + 1 = 10
10 – 1 = 9
 Bridge to 10: Using Bridge to 10 is usually easiest when adding or subtracting number sentences
with 9, 8, or 7.
Addition examples:
7 + 4 = 11
7 + 3 = 10 and 1 more is 11.
9 + 4 = 13
9 + 1 = 10 and 3 more is 13.
7 + 5 = 12
7 + 3 = 10 and 2 more is 12.
9 + 5 = 14
9 + 1 = 10 and 4 more is 14.
8 + 4 = 12
8 + 2 = 10 and 2 more is 12.
9 + 6 = 15
9 + 1 = 10 and 5 more is 15.
8 + 5 = 13
8 + 2 = 10 and 3 more is 13.
9 + 7 = 16
9 + 1 = 10 and 6 more is 16.
Subtraction examples:
14 – 9 = __________ I know 9 + 1 = 10 and 4 more = 14. That means 14 – 9 = 5.
Subtraction facts involving 8:
13 – 8 = __________
I know 8 + 2 = 10 and 3 more = 13. That means 13 – 8 = 5.
Subtraction facts involving 7:
11 – 7 = __________
I know 7 + 3 = 10 and 1 more = 11. That means 11 – 7 = 4.