# Ch 18: ACT Math: Pre-Algebra

### About This Chapter

## ACT Math: Pre-Algebra - Chapter Summary

Revisit these important pre-algebra skills that provide strong foundations for higher math concepts. In addition to including pre-algebra questions, the ACT also has questions that require you to draw on your understanding of pre-algebra to answer more advanced questions. These lessons cover the pre-algebra topics necessary for success on the ACT math portion of the test. By the end of the chapter, you'll be able to:

- Find the greatest common factor and prime factorization of a number
- Understand ratios and proportions
- Use scientific notation
- Solve problems with money
- Convert standard units of measure
- Solve problems with measurement, including length, weight, time and capacity
- Calculate percent and percentage increase and decrease
- Utilize estimation to solve mathematical problems

Short, user-friendly videos present the topics, and quizzes follow for immediate feedback. The lessons are available on your schedule and on any device.

### 1. Scientific Notation: Practice Problems

Scientific notation has a lot of exponents, but it's really not that bad - and it's really convenient for working with awkwardly big or small numbers! Get some practice here.

### 2. How to Find the Greatest Common Factor

If the factors of a number are the different numbers that you can multiply together to get that original number, then the greatest common factor of two numbers is just the biggest one that both have in common. See some examples of what I'm talking about here!

### 3. How to Find the Prime Factorization of a Number

The prime factorization of a number involves breaking that number down to its smallest parts. This lesson will show you two different ways to discover the prime factorization of any number.

### 4. How to Find the Least Common Multiple

The least common multiple of two numbers is the smallest number that can be divided evenly by your two original numbers. See some examples of what I'm talking about here!

### 5. How to Solve Problems with Money

Money matters, and knowing how much things cost will be useful no matter where you go. In this lesson, we'll learn the steps for solving word problems involving money.

### 6. Standard Units of Measurement for Length, Weight, Time & Capacity

Watch this video lesson to learn how to recognize the various units of measurement for length, weight, time and volume. Learn to recognize both U.S. units and metric units.

### 7. How to Convert Standard Units of Measure

The United States uses pounds, miles, and Fahrenheit for measurements, but the rest of the world uses the metric system. This video lesson will help you to convert from one to the other easily, so you can understand kilometers and kilograms, too.

### 8. How to Solve Problems with Measurement

In this lesson, we will use basic mathematical operations to solve problems involving perimeter, area, and volume. You will also learn a method for scaling to compare models to real structures or objects.

### 9. Calculate Percentages: Formula & Overview

Learn how understanding and being able to calculate percentages can help you when shopping and when reading test scores. Also learn how to easily convert a decimal into a percentage and vice versa.

### 10. Percentage Increase and Decrease: Calculation and Examples

After watching this video lesson, you will be able to calculate the percentage increase and decrease of changes that happen over time. You will also learn what you need in order to make your calculations.

### 11. Calculations with Ratios and Proportions

Even if only 99 out of 100 people need to know how to work with ratios, the odds that they'll be useful to you are very high. In this lesson, we'll practice performing calculations with ratios and proportions.

### 12. Solving Mathematical Problems Using Estimation

Estimating is a method of calculating a result that is close to, but not exactly, the correct answer to a math problem. Why would you ever need to do this? This lesson reviews estimating and answers the question as to why you would do it.

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### Other Chapters

Other chapters within the ACT Prep: Practice & Study Guide course

- ACT: About the Test
- ACT English: Section Overview
- ACT English: Punctuation
- ACT English: Grammar and Usage
- ACT English: Sentence Structure
- ACT English: Production of Writing
- ACT English: Style
- ACT Writing: Overview
- ACT Writing: Essay Skills
- ACT Reading: Overview
- ACT Reading: Question Types
- ACT Reading: Understanding Reading Passages
- ACT Reading: Analyzing Reading Passages
- ACT Reading: Word Meanings and Choice
- ACT Reading: Practice
- ACT Math: Overview
- ACT Math: Number & Quantity
- ACT Math: Algebraic Expressions
- ACT Math: Radicals
- ACT Math: Linear Equations
- ACT Math: Functions
- ACT Math: Types of Functions
- ACT Math: Absolute Value
- ACT Math: Matrices
- ACT Math: Inequalities
- ACT Math: Probability, Combinations & Factorial
- ACT Math: Data and Statistics
- ACT Math: Exponents
- ACT Math: Polynomials and Quadratics
- ACT Math: Rational Equations and Expressions
- ACT Math: Sequences
- ACT Math: Complex Numbers
- ACT Math: Exponentials and Logarithms
- ACT Math: Coordinate Geometry
- ACT Math: Conic Sections
- ACT Math: Triangles
- ACT Math: Plane Geometry
- ACT Math: Lines and Angles
- ACT Math: Trigonometry
- ACT Science Reasoning: Overview
- ACT Science Reasoning: Fundamentals of Science
- ACT Science Reasoning: Evaluating Models
- ACT Prep Flashcards