In Saxon Math Intermediate 4, Grade 4 students learn how to add two- and three-digit numbers with regrouping, including how to regroup ones into tens when the sum in the ones place exceeds nine. The lesson uses money manipulatives and pencil-and-paper methods to build understanding of place value during addition. Students also practice mental math strategies for adding 19 to a number and apply problem-solving skills through word problems.
Section 1
📘 Adding with Regrouping
When we add, we sometimes have to regroup because we cannot have a number larger than as the sum of any place value.
Next, you’ll see how this works with money and then apply the same method to add multi-digit numbers using pencil and paper.
Section 2
Number Sense
When adding 19 to a number, we may mentally add 20 and then think of the number that is one less than the sum.
To solve , think , then subtract one to get .
To solve , think , then subtract one to get .
To solve , think , then subtract one to get .
Adding 19 is tricky, but adding 20 is a breeze! Just add 20 to your number and then take one tiny step back to get your answer. It's a clever and super speedy shortcut for your brain.
Section 3
Adding with regrouping
When we add, we sometimes have to regroup because we cannot have a number larger than 10 as the sum of any place value.
For : add ones . Write down the 3 and carry the 1 ten. Then add tens . Your total is 53.
For : add ones . Write 2, carry the 1 ten. Add tens . The sum is 92.
You can't fit two digits in the ones place! If you have 13 ones, it’s like having too many coins. You trade ten 1-dollar bills for one 10-dollar bill and carry that new ten over to its proper column.
Section 4
Draw a Picture
We can find the answer more quickly if we draw a picture. We could draw dots or other symbols to stand for the students and then circle groups of 4 students.
For 15 students in cars that hold 5 each: Draw 15 dots, then circle groups of 5. You'll make 3 circles, so you need 3 cars.
If you have 18 cookies for 6 friends: Draw 18 dots and circle 6 at a time. You will get 3 circles, meaning each friend gets 3 cookies.
Don't just stare at a word problem, become an artist! Drawing the objects in the problem, like students as dots and cars as circles, can make the solution magically appear right on the page.
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Section 1
📘 Adding with Regrouping
When we add, we sometimes have to regroup because we cannot have a number larger than as the sum of any place value.
Next, you’ll see how this works with money and then apply the same method to add multi-digit numbers using pencil and paper.
Section 2
Number Sense
When adding 19 to a number, we may mentally add 20 and then think of the number that is one less than the sum.
To solve , think , then subtract one to get .
To solve , think , then subtract one to get .
To solve , think , then subtract one to get .
Adding 19 is tricky, but adding 20 is a breeze! Just add 20 to your number and then take one tiny step back to get your answer. It's a clever and super speedy shortcut for your brain.
Section 3
Adding with regrouping
When we add, we sometimes have to regroup because we cannot have a number larger than 10 as the sum of any place value.
For : add ones . Write down the 3 and carry the 1 ten. Then add tens . Your total is 53.
For : add ones . Write 2, carry the 1 ten. Add tens . The sum is 92.
You can't fit two digits in the ones place! If you have 13 ones, it’s like having too many coins. You trade ten 1-dollar bills for one 10-dollar bill and carry that new ten over to its proper column.
Section 4
Draw a Picture
We can find the answer more quickly if we draw a picture. We could draw dots or other symbols to stand for the students and then circle groups of 4 students.
For 15 students in cars that hold 5 each: Draw 15 dots, then circle groups of 5. You'll make 3 circles, so you need 3 cars.
If you have 18 cookies for 6 friends: Draw 18 dots and circle 6 at a time. You will get 3 circles, meaning each friend gets 3 cookies.
Don't just stare at a word problem, become an artist! Drawing the objects in the problem, like students as dots and cars as circles, can make the solution magically appear right on the page.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter