1. 1.4 Identity and Equality Properties The sum of any number and 0 is equal to the number. So, 0 is called the additive identity. a + 0 = 0 + a = a 5 + 0 = 0 + 5 = 5

2. Multiplication Properties There are also special properties associated with multiplication.

3. Identify Properties Name the property used in each equation. Then find the value of n. a.42 · n = 42 Multiplicative Identity Property n = 1, since 42 · 1 = 42. b.n + 0 = 15 Additive Identity Property n = 15, since 15 + 0 = 15. c.n · 9 = 1 Multiplicative Inverse Property n = 1/9, since 1/9 · 9 = 1.

4. Properties of Equality There are several properties of equality that apply to addition and multiplication.

5. Evaluate Using Properties Evaluate. Name the property used in each step. Substitution; 3 · 2 = 6 Substitution; 6 – 5 = 1 Multiplicative Identity; 2 · 1 = 2 Multiplicative Inverse; 3 · ⅓ = 1 Substitution; 2 + 1 = 3