Addition is combining two or more numbers to find their total. When working with four-digit numbers, we add numbers between 1,000 and 9,999.
Four-digit numbers have a thousands place, hundreds place, tens place, and ones place. Always line up the numbers by their place values when adding.
To add four-digit numbers, start from the ones place and move left, regrouping when the sum in any place is 10 or more.
Remember to add any regrouped amounts to the next column on the left. This is sometimes called "carrying over."
Regrouping happens when the sum of digits in a column is 10 or more. We write the ones digit in that column and carry the tens digit to the next column.
Let's break this down:
When regrouping, write the carried number above the next column to help you remember to add it.
Word problems describe real-life situations where we need to use addition. First, identify what needs to be added, then set up the addition problem correctly.
A library has 3,245 fiction books and 1,897 nonfiction books. How many total books does the library have?
The library has 5,142 total books.
Always read word problems carefully. Look for clue words like "total," "sum," "altogether," or "combined" that tell you to add.
After solving an addition problem, it's important to check your work to make sure your answer is correct.
Check: 3,909 - 2,341 = 1,568 ✓
Good mathematicians always check their work. This helps catch mistakes and builds confidence in your answers.