Addition Within 20
Grade 1 · Math · Study Guide
Learn how to add two numbers together to get a sum of 20 or less.
Addition means putting two groups together to find out how many there are in all. When we add, we use a plus sign (+) and an equals sign (=). For example, 5 + 3 = 8 means if you have 5 apples and someone gives you 3 more, you end up with 8 apples total.
There are lots of helpful tricks for adding! One trick is called counting on. Start with the bigger number and count up. For 6 + 4, start at 6 and count four more: 7, 8, 9, 10. Another trick is using doubles. If both numbers are the same, like 7 + 7, that equals 14. Knowing your doubles helps you solve lots of other problems too.
You can also use a number line. Put your finger on the first number and hop forward the number of spaces shown by the second number. Where you land is your answer. Adding zero is easy — any number plus zero stays the same!
| Problem | Sum |
|---|---|
| 1 + 1 | 2 |
| 2 + 2 | 4 |
| 3 + 3 | 6 |
| 4 + 4 | 8 |
| 5 + 5 | 10 |
| 6 + 6 | 12 |
| 7 + 7 | 14 |
| 8 + 8 | 16 |
| 9 + 9 | 18 |
| 10 + 10 | 20 |
Key terms
- addition
- Putting two or more groups together to find the total
- sum
- The answer you get when you add two numbers together
- plus sign (+)
- The symbol that means add
- equals sign (=)
- The symbol that means the same as or the answer is
- counting on
- A strategy where you start with the bigger number and count up
Flashcards
- 5 + 6
- 11
- 7 + 8
- 15
- 9 + 9
- 18
- Sum
- The answer to an addition problem
- 4 + 7
- 11
- 8 + 6
- 14
Practice questions
What is 8 + 5?
- 12
- 13
- 14
- 11
Show answer
Answer: 13
8 + 5: count on from 8 five times — 9, 10, 11, 12, 13
Which doubles fact equals 16?
- 7 + 7
- 8 + 8
- 9 + 9
- 6 + 6
Show answer
Answer: 8 + 8
8 + 8 = 16; the doubles fact for 16
9 + 0 = 9
Show answer
Answer: True
Any number plus zero equals that same number
6 + 7 = ___
Show answer
Answer: 13
6 + 7 = 13; count on from 7 six times or use near-doubles (6+6=12, one more = 13)
Maria has 9 crayons. She gets 4 more. How many crayons does she have now?
- 12
- 14
- 13
- 15
Show answer
Answer: 13
9 + 4 = 13; start at 9 and count on 4 more
Fun facts
- The word 'addition' comes from the Latin word 'addere' which means 'to give to'!
- You can add numbers in any order and get the same answer — 4 + 3 = 7 and 3 + 4 = 7 too!
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