Arithmetic properties: Identity property

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Intros
Lessons
  1. Introduction to the identity property of addition and multiplication (and properties of zero):
  2. Showing that a+0=aa + 0 = a
  3. Why is it called the "identity" property?
  4. Showing that a × 1 = a
  5. The general formulas for the identity property
  6. The three properties of zero involving multiplication and division (a × 0 = 0; 0 ÷ a = 0; and a ÷ 0 = undefined)
  7. The general formulas for the properties of zero
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Examples
Lessons
  1. Additive identity property of 0
    Use the additive identity of 0 to fill in the blanks.
    1. 287 + __ = 287
    2. __ + 0 = 0.39
    3. 0 + __ = 5171000 \large \frac{517}{1000}
  2. Multiplicative identity property of 1
    Use the multiplicative identity of 1 to fill in the blanks.
    1. 657 × __ = 657
    2. 1 × __ = 8.914
    3. __ × 832900\large \frac{832}{900} = 832900\large \frac{832}{900}
  3. Multiplying and dividing using properties of 0
    Use the properties of 0 to fill in the blanks.
    1. 1325\large \frac{13}{25} × 0 = __
    2. __ × 1 = 0
    3. 0 ÷ 25 = __
    4. 35 ÷ __ = undefined
    5. 7.6 × 0 = __
    6. 439 ÷ 0 = __
  4. Identity properties and all four operations
    What happens to the identity of number 46 when:
    1. 46 + 0 =
    2. 46 - 0 =
    3. 46 × 0 =
    4. 46 × 1 =
    5. 46 ÷ 1 =
    6. 46 ÷ 0 =
    7. 0 ÷ 46 =
  5. Identity properties word problem
    If aa, bb and cc are real numbers with secret identities:
    1. What happens to a when it is added to 0
    2. What happens to b when it is multiplied with 1
    3. What happens to c when it is multiplied with 0
    4. What happens to a when it is divided by 0
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Practice
Topic Notes
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In this lesson, we will learn:

  • What is the additive identity property of zero
  • What is the multiplicative identity property of one
  • How to write the general formulas/equations for the identity properties
  • What are the three properties of zero?
  • How the identity properties are different from the properties of zero
  • How to write the general formulas/equations for properties of zero

Notes:

  • The identity property is observed when the identity of the original number does NOT change after the equal sign. The answer will be the same number that you started with.
    • The numbers can be any real number (whole numbers, fractions, decimals, integers, etc.)
    • The word โ€œidentityโ€ can mean who you are or what you are


  • The identity property only happens for TWO cases in math:
    • For addition: adding zero to any number will NOT change that number
      • Ex. 8 + 0 = 8
      • Ex. 0.5 + 0 = 0.5
      • Ex. 12\large \frac{1}{2} + 0 = 12\large \frac{1}{2}
    • For multiplication: multiplying any number by one will NOT change that number
      • Ex. 8 ร— 1 = 8
      • Ex. 1.47 ร— 1 = 1.47
      • Ex. 34\large \frac{3}{4} ร— 1 = 34\large \frac{3}{4}

  • The general formulas for the identity property (where a is aa variable that represent a real number) are:

  • Arithmetic Property

    Of Addition

    Of Multiplication

    (Additive)

    Identity property of 0

    a+0=aa + 0 = a

    0+a=a0 + a = a

    *

    (Multiplicative)

    Identity property of 1

    aร—1=aa ร— 1 = a

    1ร—a=a1 ร— a = a


  • It is important to know the properties of zero โ€“ *what happens when you multiply and divide by zero so that you don't get them confused with the identity property of zero
    • There are three properties of zero:
      • (1) when you multiply by zero, the answer will always be zero
      • (2) when zero is divided by any number, the answer will always be zero
      • (3) when you attempt to divide any number by zero, the answer will always be undefined

  • The general formulas for the properties of zero are:

  • Arithmetic Property

    Of Multiplication

    Of Division

    Properties of Zero

    aร—0=0a ร— 0 = 0

    0ร—a=00 ร— a = 0

    0รทa=00 รท a = 0

    - - - - - - - - - - - - - - - - -

    aรท0=undefined a รท 0 = undefined