1. Rational Numbers, Rounding, and Order of Operations

2. Rational Numbers are any numbers that can be written as a fraction. That means: Integers Fractions Decimals

4. Rounding – Look to the right of the specified decimal place. If the number is 5 or greater, round up one. If the number is 4 or less, leave it alone. (You know this. You have been doing it forever!!!) Round 7.356894 to 3 decimal places. 7.356894 look at the number to the right of the 6 it is higher than 5 so round up. 7.357

5. Truncation – Cutoff what you don’t want. Approximate 7.456892 to 3 decimal places by truncation 7.456892 Cutoff everything past the “6” 7.456

6. Approximate 17.368204 to two decimal places by A) RoundingB) Truncation Approximate 23.02492 to two decimal places by A) RoundingB) Truncation Solution: 1. A) 17.37 B) 17.362. A) 23.02 B) 23.02

7. You know this: PEMDAS Parentheses Exponents Multiplication Division Addition Subtraction Work left to right. If you see division before multiplication, that is okay do it first. Multiplication/division and addition/subtraction are done at the same time.

8. Example 1 7 – 2 * 5 + 4 * 3 – 5 No parentheses or exponents, so look for multiplication/division 1 st. 7 – 10 + 12 – 5Go back to the beginning to do addition/subtraction. -3 + 12 – 5 9 – 5 4

9. Example 2 -3(x – y) + 4(3x – 2y)Here there are parentheses, but you cannot combine anything. You need to distribute 1 st. -3x + 3y + 12x - 8y Now combine like terms 9x – 5y

10. Try a few on your own. Ask a partner if they are right, before I show you the answers. 1. 8 * 5 - 4 + 6 ÷ 2 2. -2(5 + 3) + 7(3 – 2 * 5) 3. 3(5x – 2y) – 7(x – 3y) 4. 6x(5 + 2 - 4) – (3 * 2 ÷ 3) Solutions: 1. 392. -653. 8x + 15y4. 18x - 2