Evaluate numerical expressions involving rational numbers
Key notes:
Definition of Rational Numbers
- Rational numbers are numbers that can be expressed as a fraction p/q, where p and q are integers, and q ≠ 0.
- Includes integers, fractions, terminating and repeating decimals.
Order of Operations (PEMDAS/BODMAS)
- Parentheses / Brackets
- Exponents / Orders (Squares, Cubes, etc.)
- MD Multiplication and Division (Left to Right)
- AS Addition and Subtraction (Left to Right)
Operations with Rational Numbers
- Addition & Subtraction: Convert to a common denominator if necessary.
- Multiplication: Multiply numerators and denominators separately.
- Division: Multiply by the reciprocal of the divisor.
Working with Decimals & Fractions
- Convert between fractions and decimals for ease of computation.
- Use long division to convert fractions to decimals.
Using Negative Numbers
Follow sign rules:
- Addition/Subtraction: Same signs → Add & keep sign, Different signs → Subtract & use sign of the larger absolute value.
Multiplication/Division:
- Positive × Positive = Positive
- Negative × Negative = Positive
- Positive × Negative = Negative
Evaluating Expressions with Exponents
- Apply exponent rules (e.g., am × an = am + n).
- Square and cube rational numbers carefully.
Distributive Property
- Use a (b + c) = ab + ac when simplifying expressions.
Solving Word Problems
- Identify rational number operations from the problem statement.
- Apply the correct order of operations and check for reasonableness.
Learn with an example
Evaluate the expression.
0.2 ÷ 2 + 0.6
Write your answer as an integer or a decimal. Do not round.
First, identify the operations in the expression.
0.2 ÷ 2 + 0.6
This expression has division and addition. The order of operations says to divide before adding.
0.2 ÷ 2 + 0.6 = 0.1 + 0.6
Now, add.0.1 + 0.6 = 0.7
The value of the expression is 0.7.
Evaluate the expression.
0.3÷3×0.2
Write your answer as an integer or a decimal. Do not round.
First, identify the operations in the expression.
0.3 ÷ 3 × 0.2
This expression has division and multiplication. The order of operations says to multiply and divide from left to right.
0.3 ÷ 3 × 0.2
=0.1 × 0.2
=0.1 × 0.2
=0.02
The value of the expression is 0.02.
Evaluate the expression.
1 ÷ 2/3 – 1/2
First, identify the operations in the expression.
1 ÷ 2/3 – 1/2
This expression has division and subtraction. The order of operations says to divide before subtracting.
1 ÷ 2/3 – 1/2
= 1 x 3/2 – 1/2 To divide, multiply by the reciprocal
= 3/2 – 1/2
Now, subtract.
3/2 – 1/2
= 2/2
= 1 Reduce the fraction to lowest terms
The value of the expression is 1.
Let’s practice!🖊️