Mr. Alongi Math
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Rules & properties reference

Properties of Operations

A property is a math rule that always works. Properties let us move, group, or rewrite numbers without changing the answer.

In simple words:Properties help make math easier and explain why our algebra steps are allowed.
Before distribution6(10 + 2)
After distribution6(10) + 6(2)
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See how it moves

Distributive Property

The number outside must multiply every term inside.

5(x+3)
5 · x5 · 3
5x + 15

Why should I care?

You can use properties to do mental math, remove parentheses, simplify expressions, and solve equations.

Quick-reference chart

The Rules

Read the rule, then study the example.

Commutative Property

Change the order. The answer stays the same. This works for addition and multiplication.

Example 1: Addition4 + 9 = 9 + 4Example 2: Multiplication3 · 7 = 7 · 3It does not work for subtraction or division.

Associative Property

Change which numbers are grouped together. The answer stays the same. This works for addition and multiplication.

Example 1: Addition(2 + 5) + 8= 2 + (5 + 8)Example 2: Multiplication(2 · 3) · 4= 2 · (3 · 4)It does not work for subtraction or division.

Identity Property

Add 0 or multiply by 1. The number stays the same.

Example 1: Add zero12 + 0 = 12Example 2: Multiply by one12 · 1 = 12

Inverse Property

A number and its opposite add to 0. A number and its flipped fraction multiply to 1.

Example 1: Opposites8 + (-8) = 0Example 2: Flipped fractions3/4 · 4/3 = 1

Distributive Property

Multiply the outside number by every term inside the parentheses.

5(x + 3)5 · x + 5 · 35x + 15

Zero Property

Any number multiplied by zero equals zero.

Example 127 · 0 = 0Example 20 · x = 0

Follow the thinking

Worked Examples

Use Distribution: 7(x - 4)

  1. Multiply 7 by x: 7 · x = 7x.
  2. Multiply 7 by -4: 7 · (-4) = -28.
  3. Put the two results together.
7(x - 4) = 7x - 28

Make Mental Math Easier

  1. Start with 25 + 17 + 75.
  2. Change the order: 25 + 75 + 17.
  3. Group 25 + 75 to make 100.
  4. Add 100 + 17.
25 + 17 + 75 = 117

Watch out

Common Mistakes

  • Commutative means change the order. Associative means change the grouping.
  • Do not use the commutative property with subtraction or division.
  • When distributing, multiply every term inside the parentheses.

Check yourself

Quick Practice

1. 14 + 0 = 14

Identity property of addition.

2. Rewrite 3(x + 5)

3x + 15.

3. 6 · 4 = 4 · 6

Commutative property of multiplication.

Your turn

10-Question Properties Practice

Type the property name or rewrite the expression as requested.

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