Grade 3 · Math · Lesson 9

Add and Subtract 3- and 4-Digit Numbers

The column method lines up digits by place value so we can add or subtract one column at a time, starting from the ones. When the ones column adds up to 10 or more, we regroup (carry) the extra ten into the tens column. When we cannot subtract, we borrow (regroup) from the next column.

What this lesson teaches

1Add two 3-digit or 4-digit numbers using the column method, regrouping where needed
2Subtract two 3-digit or 4-digit numbers using the column method, borrowing where needed
3Check a sum or difference by using the inverse operation

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