In this Grade 4 enVision Mathematics lesson from Chapter 2, students learn how to subtract across zeros using the standard algorithm, including regrouping across multiple place values when zeros appear in the minuend. The lesson covers multi-digit subtraction problems such as 6,000 minus 4,678, where students must regroup from the thousands place through hundreds and tens before subtracting. Students also practice using estimation to verify that their differences are reasonable.
Section 1
Regrouping Across Zeros: The Role of 9s
When regrouping across zeros, the first non-zero digit is reduced by 1, the place value you are regrouping to becomes 10 (or 10 + its original value), and all intermediate zeros become 9. This happens because you are borrowing sequentially. For example:
Expand to review the lesson summary and core properties.
Section 1
Regrouping Across Zeros: The Role of 9s
When regrouping across zeros, the first non-zero digit is reduced by 1, the place value you are regrouping to becomes 10 (or 10 + its original value), and all intermediate zeros become 9. This happens because you are borrowing sequentially. For example: