The document explains the concept of regrouping in subtraction, outlining the need to borrow when there are insufficient ones or tens to subtract from. It describes the process of trading a ten or a hundred to facilitate the subtraction, using examples to illustrate how to complete the calculations. The step-by-step approach helps to clarify why and how regrouping is necessary for solving problems effectively.

1. WHY DO I
REGROUP AND
HOW DO I DO
IT?Let’s find out!

2. WHAT DO YOU DO
WHEN THERE ARE
NOT ENOUGH ONES
TO SUBTRACT
FROM?
➤ Let’s make a model!
➤ Now, let’s trade a ten!
➤ Why did we need to regroup?
2 2
7-

3. WHY DO WE NEED TO REGROUP?
2 2
7-
We need to regroup
because we don’t have
enough ones to take
away 7.
There are more ones
on the floor.

4. HOW DO WE REGROUP?
2 2
7-
We need to regroup by
borrowing a ten.
Go next door and get
10 more.
1

5. HOW DO WE REGROUP?
2 2
7-
We need to regroup by
borrowing a ten.
Go next door and get
10 more.
1 12

6. NOW WE CAN SOLVE THE PROBLEM
2 2
7-
We need to subtract
the ones first.
12-7 is 5 (11, 10, 9, 8,
7)
1 12
5

7. NOW WE CAN SOLVE THE PROBLEM
2 2
7-
Now, we subtract the
tens.
1-0 is 1
1 12
5

8. WHAT DO YOU DO
WHEN THERE ARE
NOT ENOUGH TENS
TO SUBTRACT
FROM?
➤ Let’s make a model!
➤ Now, let’s trade a hundred!
2 5
5-
8
9
0

9. WHY DO WE NEED TO REGROUP?
8 5
5-
We need to regroup
because we don’t have
enough tens to take
away 9 tens.
There are more tens on
the floor.
2
9
0

10. HOW DO WE REGROUP?
8 5
5-
We need to regroup by
taking 1 hundred and
give it to the tens.
Go next door and get
ten more.
2
9
0
1

11. HOW DO WE REGROUP?
8 5
5-
We need to regroup by
taking 1 hundred and
give it to the tens.
Go next door and get
ten more.
2
9
0
1 18

12. NOW WE CAN FINISH SOLVING
8 5
5-
We already subtracted
the ones, so now we
subtract the tens.
18-9= 9 because I
know 9+9=18.
2
9
0
1 18
9

13. NOW WE CAN FINISH SOLVING
8 5
5-
We already subtracted
the tens, so now we
subtract the hundreds.
1-0=1, so the answer is
190
2
9
0
1 18
9
0
1