Accessible Algorithms For Subtraction - Subtraction Cheat Sheet Page 2
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1
2Subtract Decimals with Ungrouping
The Ungroup First Method works equally well to develop facility
with decimal subtraction.
Left-to-Right
Right-to-Left
12 12
12 12
4
13
13
12
4
2
2
12
$ 5
3
. 3
2
$ 5
3
. 3
2
2 7. 6 5
2 7. 6 5
2 5. 6 7
2 5. 6 7
Subtract Fractions with Ungrouping
There are multiple methods for ungrouping mixed numbers for
subtraction. Struggling students may find the Expanded Notation
Method, shown below, beneficial.
1
4
1
5
6
5
5
4
4
4
4
3
3
2
2
4
4
2
3
Ungrouping Mixed
4
Numbers
Other students may choose to cancel and ungroup, as in this
The typical “smaller from
example.
larger” error that is common
5
in multi-digit subtraction also
5
4
occurs with the subtraction
1
6
of mixed numbers. Some
4
students may try to subtract
3
2
the smaller fraction from the
4
larger fraction even when it
2
means “going the wrong
3
4
way.” Encouraging these
students to use the vertical
format is often helpful
because it looks like the
ungrouping in multi-digit
subtraction that they
already know.
Level 2
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