# Basic Math & Pre-Algebra

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### Recognize Even and Odd Numbers, and Multiples of 3, 4, and 5

A number sequence is an arrangement of numbers according to a rule. For example, you can have a sequence of numbers that are odd or even, or multiples of 3, 4, 5, and so on.

### How to Find Square Numbers

You get a square number by multiplying a number by itself, so knowing the square numbers is a handy way to remember part of the multiplication table. Although you probably remember without help that 2

### How to Identify Prime Numbers

A prime number can be divided by only itself and 1. This makes it stubborn. Like certain people you may know, a prime number resists being placed in any sort of a box. Look at how the number 13 is depicted

### How to Add and Subtract on the Number Line

You can use the number line to demonstrate simple addition and subtraction. These first steps in math become a lot more concrete with a visual aid. Here’s the main thing to remember:

### Use the Number Line to Find Zero

An important addition to the number line is the number 0, which means nothing, zilch, nada. Step back a moment and consider the bizarre concept of nothing. For one thing — as more than one philosopher

### How to Multiply with the Number Line

Suppose you start at 0 and circle every other number on a number line, as shown in the below figure. As you can see, all the even numbers are now circled. In other words, you’ve circled all the multiples

### How to Divide Numbers on the Number Line

You can use the number line to divide. For example, suppose you want to divide 6 by some other number. First, draw a number line that begins at 0 and ends at 6, as in the following figure.

### How to Tell Placeholders from Leading Zeros

It is important to know when a zero is a placeholder, and when it is a leading zero. Although the digit 0 adds no value to a number, it generally acts as a placeholder to keep the other digits in their

### How to Read Long Numbers

When you write a long number, you use commas to separate periods. Periods are simply groups of three numbers. They help make long numbers more readable. For example, here’s about as long a number as you’ll

### How to Round Numbers

Rounding numbers makes long numbers easier to work with. Here you will learn how to round numbers to the nearest ten, hundred, thousand, and beyond.

### How to Estimate Values to Make Problems Easier

If you know how to round numbers, you can use this skill in estimating values. Estimating saves you time by allowing you to avoid complicated computations and still get an approximate answer to a problem

When you want to add large numbers, you can stack them on top of each other so that the ones digits line up in a column, the tens digits line up in another column, and so on. You then add column by column

### How to Borrow When Subtracting

Sometimes, when you are subtracting large numbers, the top digit in a column is smaller than the bottom digit in that column. In that case, you need to borrow from the next column to the left. Borrowing

### How to Do Inverse Operations

Each of the Big Four operations (addition, subtraction, multiplication, division) has an inverse — an operation that undoes it. Addition and subtraction are inverse operations because addition undoes subtraction

### How to Do Commutative Operations

Addition and multiplication are both commutative operations. Commutative means that you can switch around the order of the numbers without changing the result. This property of addition and multiplication

### How to Perform Associative Operations

Addition and multiplication are both associative operations, which means that you can group them differently without changing the result. This property of addition and multiplication is also called the

### How to Use the Distributive Property of Multiplication

In math, distribution (also called the distributive property of multiplication over addition) allows you to split a large multiplication problem into two smaller ones and add the results to get the answer

### How to Add, Subtract, Multiply, and Divide with Units

Anything that can be counted is a unit. Because you can count units, this means that you can apply the Big Four operations (addition, subtraction, multiplication, and division) to them.

### How to Represent Inequalities in Equations

Sometimes, you want to talk about when two quantities are different. These statements are called inequalities. Four types of inequalities are (doesn’t equal), <

### Find the Square Root of a Number

A square root is the most common root operation. A root is the inverse operation of an exponent (which means that it undoes an exponential operation), and so a

### Evaluate Mathematical Expressions

The ideas of equality, expressions, and evaluation are vital concepts when working with equations.An equation is a mathematical statement that tells you that two things have the same value — in other words

### How to Solve Equations with Parentheses

In math, parentheses — ( ) — are often used to group together parts of an expression. This helps you to find the order of precedence when you work with equations. When it comes to evaluating expressions

### How to Plug in Numbers to Solve a Word Equation

When you write out a word equation, you have the facts you need in a form you can use to find the solution. You can often solve the problem by plugging numbers from one word equation into another. The

### How to Solve Complex Word Problems

To solve complex word problems, you use the same skills as when you solve basic word problems, but the calculations become harder. For example, instead of a dress costing an amount such as

### Find the Absolute Value of a Number

The absolute value of a number is the positive value of that number. It tells you how far away from 0 a number is on the number line. The symbol for absolute value is a set of vertical bars.