Subtraction with Regrouping

1
Subtraction with Regrouping

• Mrs. Walker 4th Grade

2
Difference

• The answer to a subtraction problem!

100 25 75
3
Inverse Operations

• Opposite operations.
• This means that one operation undoes the other.
• Example Addition and Subtraction

100 25 75 75 25 100
4
Subtraction Rules

• When you subtract 0 from any number, the result
  is the number.
• 6-06 4-04
• 2. When you subtract any number from itself, the
  result is 0.
• 6-60 5-50

5
7
2
You cant take 4 from 2 so you must regroup the
72.
6
tens
ones
7
2
Lets just think about the 72 for a minute.
Remember the place value columns.
Put 72 in expanded form 70 2
You can borrow 10 from the 70 and give it to the
2 and still have 72.
7
7
2
Now lets get back to the original problem.
You cant take 4 from 2 so you must regroup the
72.
Remember youre actually taking 10 from 70
3
8
Now subtract.
Lets read the completed problem 72 34 38
8
3
8
You cant take 6 from 3 so you must regroup the
83.
Remember youre actually taking 10 from 80
5
7
Now subtract.
Lets read the completed problem 83 26 57
9
5
9 6 7
1
2 3 9
-
8
2
7
10
8
6 9 2
1
4 3 7
-
5
5
2
11
5
7
1
1
1
2 8 6 5
1
,
8 6 8
-
7
9
1
9
,
12
Practice in your notes!

• 3,214 - 957
• 4,275 - 1,345
• 1,542 481
• 2,962 845

13
What do we do if the numbers we need to subtract
have a decimal point?
14
Its easy! Follow these steps

1. Line up the decimal points and subtract the
   columns from right to left, regrouping as needed.
2. Place a decimal point in the answer directly
   below the other decimal points.

15
5
9 . 6 7
1
2 . 3 9
-
.
8
2
7
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Subtraction Words

• Difference 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?

17
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.
-
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Name
Directions For each problem, roll two
dice. Write each number you roll in a box then
solve.