In this Grade 4 Saxon Math lesson, students learn how to subtract two-digit numbers using regrouping, also called borrowing or exchanging, by trading 1 ten for 10 ones when the ones digit is too small to subtract from. The lesson uses money manipulatives and real-world dollar amounts to build understanding of the regrouping process. Students practice applying this skill to subtract two-digit monetary values and standard numbers with pencil and paper.
Section 1
📘 Subtracting Two-Digit Numbers with Regrouping
Trading 1 ten for 10 ones is an example of regrouping, or exchanging.
Next, you'll use money manipulatives and drawings to practice regrouping, then solve subtraction problems using pencil and paper.
Section 2
Guess and Check
A problem-solving strategy where you make a reasonable guess, check if it fits the problem's conditions, and revise your guess if it is wrong. Repeat the process until you find the correct answer.
Think of yourself as a super sleuth! Make a smart guess to crack the case, check your clues, and if you're wrong, just try another angle. Every guess gets you closer to the solution, detective!
Section 3
Regrouping
When subtracting, if a digit in the top number is smaller than the digit below it, you must regroup. This means trading 1 from the next higher place value for 10 of the current place value.
You can't subtract 9 from 3! Regrouping is like trading a ten-dollar bill for ten one-dollar bills. You still have the same total value, but now you have enough ones to subtract from.
Section 4
Renaming Numbers For Subtraction
A number's total value remains the same even when its place values are regrouped. For instance, 5 tens and 3 ones is equal to 4 tens and 13 ones.
Think about money! Having 5 ten-dollar bills and 3 one-dollar bills is the same as having 4 ten-dollar bills and 13 one-dollar bills. The total is still 53 dollars, but the bills are just arranged differently.
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Section 1
📘 Subtracting Two-Digit Numbers with Regrouping
Trading 1 ten for 10 ones is an example of regrouping, or exchanging.
Next, you'll use money manipulatives and drawings to practice regrouping, then solve subtraction problems using pencil and paper.
Section 2
Guess and Check
A problem-solving strategy where you make a reasonable guess, check if it fits the problem's conditions, and revise your guess if it is wrong. Repeat the process until you find the correct answer.
Think of yourself as a super sleuth! Make a smart guess to crack the case, check your clues, and if you're wrong, just try another angle. Every guess gets you closer to the solution, detective!
Section 3
Regrouping
When subtracting, if a digit in the top number is smaller than the digit below it, you must regroup. This means trading 1 from the next higher place value for 10 of the current place value.
You can't subtract 9 from 3! Regrouping is like trading a ten-dollar bill for ten one-dollar bills. You still have the same total value, but now you have enough ones to subtract from.
Section 4
Renaming Numbers For Subtraction
A number's total value remains the same even when its place values are regrouped. For instance, 5 tens and 3 ones is equal to 4 tens and 13 ones.
Think about money! Having 5 ten-dollar bills and 3 one-dollar bills is the same as having 4 ten-dollar bills and 13 one-dollar bills. The total is still 53 dollars, but the bills are just arranged differently.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter