Lesson
Page
Operations 



Inverse
Operations
are two operations that
have the opposite effect,
such as addition and subtraction,
or multiplication and division.
For Inverse
Operations we can form
Fact Families.
In the Fact
Family of (2, 3, and 5)
we can form two addition
and two subtraction problems.
2 +
3 = 5
3 + 2 = 5
5  3 = 2
5  2 = 3
Addition/Subtraction
Examples:
Fact Family of (2,
4, 6)
2
+ 4 = 6
4 + 2 = 6
6  2 = 4
6  4 = 2
Fact Family of (3,
5, 8)
3
+ 5 = 8
5 + 3 = 8
8  3 = 5
8  5 = 3
In Addition/Subtraction
Fact Families,
the largest number in the "family" is
*the total number you get when you Add,
and
*the total number you Subtract from.
In the Fact
Family of (3, 4, and 12)
we can form two multiplication
and two division problems.
3 x
4 = 12
4 x
3 = 12
12 3 =
4
12 4 = 3
Multiplication/Division
Examples:
Fact Family of (2,
3, 6)
2
x
3 = 6
3 x
2 = 6
6
2 = 3
6
3 = 2
Fact Family of (4,
5, 20)
4
x
5 = 20
5 x
4 = 20
20
4 = 5
20
5 = 4
In Multiplication/Division
Fact Families,
the largest number in the "family" is
*the total number you get when you Multiply,
and
*the total number you Divide up (dividend).
Knowing how Fact
Families are related
and work together
helps you see the 'relation' between
adding and subtracting or multiplying
and dividing.
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