Second Grade Math: One-Digit Addition - Sums Up to 20

What is addition?

Addition is the process of putting numbers together to find the total, or sum.

Examples:

Note

The answer in an addition problem is called the sum. The numbers being added are called addends.

You can recognize addition problems when you see the plus sign (+). It means “put together” or “combine.”

Examples:

Note

If you see the plus sign, you are adding. Always look for it in the problem.

There are different strategies you can use to solve addition problems with sums up to 20.

Strategies:

Count On: Start with the bigger number and count on. Example: 7 + 3 → start at 7, count 3 more (8, 9, 10).
Make Ten: Break apart numbers to make 10. Example: 8 + 2 = 10, or 9 + 6 → (9 + 1 = 10, then 10 + 5 = 15).
Use Doubles: Remember facts like 6 + 6 = 12. They help with near doubles (6 + 7 = 13).

Note

Choosing the right strategy can make adding faster and easier. Practice different ways so you feel confident.

Addition problems can also appear in word problems. Read carefully to understand what is being added together.

Examples:

“Sam has 5 apples. He gets 3 more. How many apples does he have now?” → 5 + 3 = 8
“There are 7 birds on a tree. 6 more fly over. How many birds are there?” → 7 + 6 = 13

Note

Look for words like in all, together, or how many. These are clues that tell you to add.

Some addition facts are so common that you should try to remember them quickly.

Important facts:

0 + any number = that number (Example: 0 + 6 = 6)
1 + any number = the next number (Example: 1 + 8 = 9)
Doubles: 2 + 2 = 4, 3 + 3 = 6, 4 + 4 = 8, 5 + 5 = 10, 6 + 6 = 12, 7 + 7 = 14, 8 + 8 = 16, 9 + 9 = 18

Note

Knowing these facts by heart will make solving other problems with sums up to 20 much faster.