subtraction with regrouping

Subtraction with Regrouping

Mrs. Walker 4th Grade

DifferenceThe answer to a

subtraction problem!

100 – 25 = 75

Inverse OperationsOpposite operations.

This means that one operation undoes the other.

Example: Addition and Subtraction

100 – 25 = 7575 + 25 = 100

Subtraction Rules

1. When you subtract 0 from any number, the result is the number.

6-0=6 4-0=4

2. When you subtract any number from itself, the result is 0.

6-6=0 5-5=0

7 23 4

You can’t take 4 from 2

so you must regroup the

72.

7 2Let’s just think about the 72 for a minute.

Remember the place

value columns.

tens

ones

Put 72 in expanded form: 70 + 2You can borrow 10 from the 70

and give it to the 2 and still have 72.

7 0 6 0borrow 10 1 2

2 give 10

7 27 2

+ +

Now let’s get back to the original problem.

7 23 4

You can’t take 4 from 2

so you must regroup the

72.

6

\Borrow 1 ten from the 7.

12Give the 1 ten

to the 2 to make 12.

Now subtract.3 8Let’s read the completed problem:

72 – 34 = 38

Remember you’re actually

taking 10 from 70

313Give the 1 ten

to the 3 to make 13.

87

\Borrow 1 ten from the 8.

2 6

You can’t take 6 from 3

so you must regroup the

83.

Now subtract.5 7Let’s read the completed problem:

83 – 26 = 57

Remember you’re actually

taking 10 from 80

Practice in your notes!

• 3,214 - 957=

• 4,275 - 1,345=

• 1,542 – 481 =

• 2,962 – 845 =

Its easy! Follow these steps:

1.1. Line up the decimal points Line up the decimal points and subtract the columns and subtract the columns

from right to left, regrouping from right to left, regrouping as needed.as needed.

2.2. Place a decimal point in the Place a decimal point in the answer directly below the answer directly below the

other decimal points.other decimal points.

Subtraction WordsSubtraction WordsDifference Fewer

How many more How much more

Left Less

Minus Remains

Subtract Were Not

Words ending with “-er”

(higher, longer, faster, heavier, larger, shorter, slower, farther, etc.)

Example: Jean's apple weighs 100 grams, and Karen's apple weighs 80 grams. How much heavier is Jean's apple?

Word Problem Practice:

Mr. Tyson flew 1,224 miles in May and he flew 2,145 miles in June. How many more

miles did he fly in June than in May?

2,145

1,224

921

Is this what you have on your paper?

Now, you write a word problem requiring subtraction to solve it.

-

7 2

Name

6 4 8 3 3 1 6 0 4 2

2 5 7 3 8 2 7 5 2 1 9 3

5 0 7 1 4 3 9 1 2 0 5 2

3 3 6 2 9 4 3 2 4 4 7 0

Directions: For each problem, roll two dice.Write each number you roll in a box then solve.