Regrouping Regrouping for for
Double-Digit Double-Digit SubtractionSubtraction
Two-Digit Subtraction – Regrouping
Two approaches:Two approaches:
Two-Digit Subtraction – Regrouping
““10 First” Approach10 First” Approach
Common ApproachCommon Approach
1. “10 First” Approach1. “10 First” Approach
Two-Digit Subtraction – Regrouping
66
2323--1616
Start with subtracting the units columnStart with subtracting the units column
Two-Digit Subtraction – Regrouping
2323--1616
33 66
First, put 3 on Mathline First, put 3 on Mathline
Two-Digit Subtraction – Regrouping
2233--1616
Can we subtract six?Can we subtract six?
Two-Digit Subtraction – Regrouping
2323--1616
66
2233--1616
66
No, 3 is less than 6No, 3 is less than 6
Two-Digit Subtraction – Regrouping
So we need to regroupSo we need to regroup
2323--1616
66
10 First Approach!10 First Approach!
Two-Digit Subtraction – Regrouping
2323--1616
66
Start by clearing the Start by clearing the MathLineMathLine
Two-Digit Subtraction – Regrouping
2323--1616
66
Count 10 from right and Count 10 from right and move overmove over
Two-Digit Subtraction – Regrouping
2323--1616
66
This is regroupingThis is regrouping
Two-Digit Subtraction – Regrouping
1 1
One ten becomes ten onesOne ten becomes ten ones
2233--1616
66
Now put the 3 ones backNow put the 3 ones back
Two-Digit Subtraction – Regrouping
1 1
2323--1616
66
Now put the 3 ones backNow put the 3 ones back
Two-Digit Subtraction – Regrouping
1 133 66
2323--1616
66
Two-Digit Subtraction – Regrouping
1 133 66
See 13See 13
2323--1616
66
Now take 13 minus 6Now take 13 minus 6
Two-Digit Subtraction – Regrouping
1 133 66
123456
2323--1616
66
See 7See 7
Two-Digit Subtraction – Regrouping
1 133 6677
Now we clear the MathLine
to subtract the tens column
Two-Digit Subtraction – Regrouping
2323--1166
1
77
1
Count ten rings on MathLine
Two-Digit Subtraction – Regrouping
2323--1616 7
11
77
Two-Digit Subtraction – Regrouping
2323--1166 7
11
77Then subtract 10
Count ten rings on MathLine
Two-Digit Subtraction – Regrouping
2323--1166 7
11
77
See zero on MathLine
00
2. Common Approach2. Common Approach
Two-Digit Subtraction – Regrouping
66
2323--1616
Start with subtracting the units columnStart with subtracting the units column
Two-Digit Subtraction – Regrouping
2323--1616
33 66
First, put 3 on Mathline First, put 3 on Mathline
Two-Digit Subtraction – Regrouping
2233--1616
Can we subtract six?Can we subtract six?
Two-Digit Subtraction – Regrouping
2323--1616
66
2233--1616
66
No, 3 is less than 6No, 3 is less than 6
Two-Digit Subtraction – Regrouping
So we need to regroupSo we need to regroup
2233--1616
66
Common Approach!Common Approach!
Two-Digit Subtraction – Regrouping
2323--1616
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
Two-Digit Subtraction – Regrouping
1
2323--1616
Two-Digit Subtraction – Regrouping
1 2
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
1 2 3
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5 6
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5 6 7
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5 6 7 8
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5 6 7 8 9
2323--1616
Two-Digit Subtraction – Regrouping
Count 10 rings from Count 10 rings from the right side to regroup.the right side to regroup.
2 31 4 5 6 7 8 9 10
2323--1616
66
Explain this ten came Explain this ten came from the tens column from the tens column
1 1
Two-Digit Subtraction – Regrouping
Move rings to the left. Move rings to the left.
This is regrouping! This is regrouping!
2233--1616
Two-Digit Subtraction – Regrouping
2233--1166
1 1Next, subtract 13 minus 6 Next, subtract 13 minus 6
123456
1
Two-Digit Subtraction – Regrouping
2323--1616
1 1
See 7 in the ones columnSee 7 in the ones column
77
1
Now we clear the MathLine
to subtract the tens column
Two-Digit Subtraction – Regrouping
2323--1166
1
77
1
Count ten rings on MathLine
Two-Digit Subtraction – Regrouping
2323--1616 7
11
77
Two-Digit Subtraction – Regrouping
2323--1166 7
11
77Then subtract 10
Count ten rings on MathLine
Two-Digit Subtraction – Regrouping
2323--1166 7
11
77
See zero on MathLine
00