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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