In this Grade 4 Eureka Math lesson from Chapter 5, students practice using place value understanding to decompose larger units into smaller units up to three times in order to subtract multi-digit whole numbers using the standard subtraction algorithm. Students work through problems requiring regrouping across the ones, tens, hundreds, and thousands places, such as solving 22,397 minus 3,745 by unbundling thousands and ten thousands. The lesson also applies the algorithm to real-world word problems using tape diagrams to represent the whole, known part, and unknown part.
Section 1
Decomposing Place Value Units
A larger place value unit can be decomposed (unbundled) into 10 of the next smaller place value units without changing the total value of the number. This relationship can be expressed as:
.
For example: , and .
Section 2
Subtracting Across Zeros
When using the subtraction algorithm, if you need to decompose a unit from a place value that is zero, you must move to the next non-zero digit to the left. Decompose 1 unit from that place, which becomes 10 in the place to its right. Continue this process, changing each intermediate zero to a 9, until you can add 10 to the original place value you needed to regroup for.
Section 3
Model Subtraction with Tape Diagrams
A tape diagram for subtraction shows a 'whole' amount divided into a 'known part' and an 'unknown part'. To find the unknown part, subtract the known part from the whole.
Expand to review the lesson summary and core properties.
Section 1
Decomposing Place Value Units
A larger place value unit can be decomposed (unbundled) into 10 of the next smaller place value units without changing the total value of the number. This relationship can be expressed as:
.
For example: , and .
Section 2
Subtracting Across Zeros
When using the subtraction algorithm, if you need to decompose a unit from a place value that is zero, you must move to the next non-zero digit to the left. Decompose 1 unit from that place, which becomes 10 in the place to its right. Continue this process, changing each intermediate zero to a 9, until you can add 10 to the original place value you needed to regroup for.
Section 3
Model Subtraction with Tape Diagrams
A tape diagram for subtraction shows a 'whole' amount divided into a 'known part' and an 'unknown part'. To find the unknown part, subtract the known part from the whole.