In this Grade 4 Saxon Math lesson, students learn how to add three-digit numbers with regrouping, applying the skill to adding money amounts such as $675 + $175. Using both money manipulatives and the standard pencil-and-paper algorithm, students practice regrouping ones into tens and tens into hundreds to find sums accurately.
Section 1
📘 Adding Three-Digit Numbers
We can exchange 10 ones for 1 ten and 10 tens for 1 hundred. This process is called regrouping.
Next, you’ll apply this regrouping method to add money and solve word problems, solidifying your understanding of place value.
Section 2
Adding Three-Digit Numbers
To add large numbers, stack them vertically. Add the ones column first, then tens, then hundreds. If a column's sum hits 10 or more, you regroup by carrying the extra digit to the next column on the left. This is just like trading ten 1 dollar bills for one 10 dollar bill.
Example 1: Add 579 dollars and 186 dollars by aligning them vertically and regrouping.
Section 3
Justify
Why can we use 100 dollars bills, 10 dollars bills, and 1 dollar bills to represent an addition problem? Our number system is base-10, meaning each place value is ten times larger than the one to its right. Money conveniently follows the exact same structure, making it a perfect model.
Example 1: The number 456 represents a value equal to four 100s, five 10s, and six 1s.
Example 2: Adding 121 + 132 is like combining a group of bills with another to find the total value.
Example 3: Therefore, 456 dollars can be shown with four 100 dollars bills, five 10 dollars bills, and six 1 dollar bills.
Think of the number 285. It's really just 2 hundreds, 8 tens, and 5 ones. This perfectly matches two 100 dollars bills, eight 10 dollars bills, and five 1 dollar bills. Math is basically money management without the shopping spree!
Section 4
Represent
Numbers can be shown with words ('nine hundred thirteen'), digits (913), or symbols (75 > -80). Mastering these translations helps you understand number relationships and communicate mathematically. It’s like being fluent in different math languages, making you a versatile problem-solver who can tackle any challenge.
Example 1: The words 'seven hundred forty-three' are written with digits as 743.
Example 2: The number 913 can be written out in words as 'nine hundred thirteen.'
Example 3: The phrase 'fifty is greater than negative one hundred' is written with symbols as 50 > -100.
Think of it as having a secret decoder ring for math! 'Seven hundred forty-three' is the word form, and '743' is the digit form. They mean the same thing. Being able to translate between them makes you a math multilingual master!
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Section 1
📘 Adding Three-Digit Numbers
We can exchange 10 ones for 1 ten and 10 tens for 1 hundred. This process is called regrouping.
Next, you’ll apply this regrouping method to add money and solve word problems, solidifying your understanding of place value.
Section 2
Adding Three-Digit Numbers
To add large numbers, stack them vertically. Add the ones column first, then tens, then hundreds. If a column's sum hits 10 or more, you regroup by carrying the extra digit to the next column on the left. This is just like trading ten 1 dollar bills for one 10 dollar bill.
Example 1: Add 579 dollars and 186 dollars by aligning them vertically and regrouping.
Section 3
Justify
Why can we use 100 dollars bills, 10 dollars bills, and 1 dollar bills to represent an addition problem? Our number system is base-10, meaning each place value is ten times larger than the one to its right. Money conveniently follows the exact same structure, making it a perfect model.
Example 1: The number 456 represents a value equal to four 100s, five 10s, and six 1s.
Example 2: Adding 121 + 132 is like combining a group of bills with another to find the total value.
Example 3: Therefore, 456 dollars can be shown with four 100 dollars bills, five 10 dollars bills, and six 1 dollar bills.
Think of the number 285. It's really just 2 hundreds, 8 tens, and 5 ones. This perfectly matches two 100 dollars bills, eight 10 dollars bills, and five 1 dollar bills. Math is basically money management without the shopping spree!
Section 4
Represent
Numbers can be shown with words ('nine hundred thirteen'), digits (913), or symbols (75 > -80). Mastering these translations helps you understand number relationships and communicate mathematically. It’s like being fluent in different math languages, making you a versatile problem-solver who can tackle any challenge.
Example 1: The words 'seven hundred forty-three' are written with digits as 743.
Example 2: The number 913 can be written out in words as 'nine hundred thirteen.'
Example 3: The phrase 'fifty is greater than negative one hundred' is written with symbols as 50 > -100.
Think of it as having a secret decoder ring for math! 'Seven hundred forty-three' is the word form, and '743' is the digit form. They mean the same thing. Being able to translate between them makes you a math multilingual master!
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter