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What is an Integer? Definition, Rules, and Examples

integer definition

What is an integer? Integers are one of the most fundamental concepts in mathematics. They form the backbone of arithmetic and number theory, and understanding them is essential for solving a wide range of mathematical problems.

In this blog, we will explore what integers are, the different types of integers, how they are represented on a number line, and the rules for performing basic operations with integers. We will also provide examples to help solidify your understanding of this important mathematical concept.

What is an Integer?

Integers are whole numbers that can be positive, negative, or zero. Some examples of integers include -3, -1, 0, 2, and 5. Consecutive integers are integers that follow each other in order from smallest to largest by 1. For example, 1, 2, 3, and 4 are called consecutive integers.

These numbers are commonly used in various mathematical operations, such as addition, subtraction, multiplication, and division. Integers do not have fractional or decimal parts, making them essential for counting and ordering. The set of integers is denoted by the symbol , which comes from the German word “Zahlen,” meaning “numbers.” Integers are a subset of real numbers and include all whole numbers and their negatives.

Set of Integers

The set of integers includes all whole numbers and their negative counterparts. This set is infinite in both the positive and negative directions. The set of integers can be written as:

ℤ = {…, -3, -2, -1, 0, 1, 2, 3, …}

This set includes:

Types of Integers

Integers can be classified into three main categories:

1. Zero

Zero is a unique integer that is neither positive nor negative. It serves as the neutral element in addition and subtraction, meaning that adding or subtracting zero from any number leaves the number unchanged. For example:

2. Positive Integers

Positive integers are whole numbers greater than zero. They are used to represent quantities that are above a reference point, such as the number of students in a class or the amount of money in a bank account. Examples of positive integers include 1, 2, 3, 4, and so on.

3. Negative Integers

They are whole numbers less than zero. They are used to represent quantities that are below a reference point, such as temperatures below freezing or debts.

Integers on a Number Line

A number line is a visual representation of numbers as points on a straight line. Integers are evenly spaced on the number line, with zero at the center. Positive integers are located to the right of zero, and negative integers are located to the left of zero.

The number line helps us understand the relative positions of integers and is particularly useful for visualizing the addition and subtraction of integers.

Integer Operations

The basic Maths operations performed on integers are:

However, the rules for these operations differ slightly from those for positive numbers, especially when negative numbers are involved. Let’s explore each operation in detail.

Addition of Integers

Adding integers is a fundamental operation in mathematics, and it’s essential for solving a wide range of problems. The rules for adding integers depend largely on their signs—whether they are positive, negative, or a combination of both. Let’s break down the rules and give examples to make this concept clearer.

1. Adding Two Positive Integers

When you add two positive numbers, the result is always a positive integer. This is straightforward because both numbers are on the positive side of the number line, and adding them together increases the total value.

Example 1:

3+5=8

In this case, both 3 and 5 are positive, and their sum is 8, which is also positive. The sum of any two positive integers will always be positive, and the final value will simply be the total of both values.

Example 2:

10+25=35

Adding 10 and 25 results in 35, which is again a positive integer.

2. Adding Two Negative Integers

When adding two negative whole numbers, the result is always negative. Since both numbers are on the negative side of the number line, the sum will also be negative, and the result will be the total magnitude of both negative numbers.

Example 1:

(−4)+(−2)=−6

Here, both -4 and -2 are negative. When added together, their absolute values are 4 and 2, respectively. Since they are both negative, the sum is also negative, and the result is -6. The rule is simple: when adding two negative numbers, add their absolute values and give the result a negative sign.

Example 2:

(−8)+(−5)=−13

Adding -8 and -5 results in -13, as both numbers are negative. The sum is the total magnitude (8 + 5 = 13) with the negative sign.

3. Adding Positive and Negative Integers

This rule can be a bit trickier because the result depends on the relative size of the two numbers. To add a negative and a positive number, you follow these steps:

This rule can be thought of as a “distance” problem, where you start at zero and move in both directions on the number line—toward the positive side and toward the negative side—and the result will depend on which direction you end up.

Example 1:

Example 2:

Subtraction of Integers

Subtracting integers involves calculating the difference between two integers. The rules for subtracting integers may seem a bit tricky at first, but with a solid understanding of negative and positive numbers, it becomes much easier to grasp. Below are the key rules for subtracting integers:

1. Subtracting a Positive Integer

When subtracting a positive integer from another integer, you follow these steps:

For example:

2. Subtracting a Negative Integer

When subtracting a negative number, it is essentially the same as adding the positive counterpart of that number. This happens because subtracting a negative number is the same as “removing” the negative sign, which transforms the operation into an addition.

For example:

3. Subtracting a Negative Integer from a Positive Integer

This scenario can sometimes lead to a little confusion, but once you follow the rule of changing subtraction to addition, it becomes clear.

For example:

4. Subtracting a Positive Integer from a Negative Integer

When you subtract a positive number from a negative one, the process is similar, but the signs of the result will depend on the comparison between the absolute values.

For example:

Multiplication of Integers

Multiplying integers involves finding the product of two or more integers. While the process is fairly straightforward, the main challenge comes from understanding how the signs of the integers affect the final result.

If both integers that you are multiplying have the same sign, whether it is negative or positive, the answer will be positive. If both integers have different signs, the answer will be negative.

1. Multiplying Two Positive Integers

When you multiply two positive numbers, the product is always positive. The process follows the basic rules of multiplication that you would apply to any two whole numbers.

For example:

2. Multiplying a Positive Integer by a Negative Integer

When you multiply a positive number by a negative number, the product is always negative. This is because multiplying by a negative number means reversing the direction of the result on the number line.

For example:

3. Multiplying Two Negative Integers

When you multiply two negative numbers, the product is always positive. This happens because multiplying two negatives “cancel out” the negative signs, effectively making the product positive.

For example:

4. Zero in Multiplication

When multiplying by zero, the product is always zero, regardless of the other integer’s sign. This is a fundamental rule in multiplication.

For example:

In both cases, multiplying by zero results in zero.

5. Multiplicative Inverse Property

The multiplicative inverse property states that for any non-zero number a, there exists a number 1/a such that when aaa is multiplied by 1/a, the result is 1. In other words, a × 1/a=1. This property is essential in solving equations and understanding the concept of division in mathematics, as it allows us to “undo” multiplication.

Division of Integers

Dividing integers is similar to multiplying them, but with the added challenge of understanding how the signs of the integers affect the result. The key to dividing integers is recognizing how the division operation interacts with positive and negative numbers. Below are the rules and explanations for dividing integers.

1. Dividing Two Positive Integers

When you divide one positive integer by another, the result is always positive. The division process follows the same basic rules you would apply to any division of positive numbers.

For example:

2. Dividing a Positive Integer by a Negative Integer

When you divide a positive integer by a negative integer, the result is always negative. This is because dividing by a negative number flips the sign of the quotient.

For example:

3. Dividing a Negative Integer by a Positive Integer

When you divide a negative integer by a positive integer, the result is always negative. This follows the same logic as the previous rule, but with the signs reversed.

For example:

4. Dividing Two Negative Integers

When you divide one negative integer by another negative integer, the result is always positive. This happens because dividing two negative numbers “cancels out” the negative signs, just as in multiplication.

For example:

5. Zero in Division

Dividing by zero is undefined in mathematics. Division by zero does not result in any meaningful number, and any attempt to divide by zero is considered an error.

For example:

However, dividing zero by any non-zero number results in zero.

For example:

Conclusion

Integers are a fundamental concept in mathematics, encompassing all whole numbers and their negatives. They are used in a wide range of applications, from everyday scenarios like measuring temperature to complex mathematical calculations. Understanding the rules for adding, subtracting, multiplying, and dividing integers is essential for solving mathematical problems and building a strong foundation in mathematics.

By mastering integers, you will be better equipped to tackle more advanced topics in algebra, calculus, and beyond. Whether you’re a student, a teacher, or just someone interested in mathematics, integers are a concept worth exploring in depth.

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Frequently Asked Questions on Integers

Q1: What are examples of integers?

An example of an integer is any whole number that does not have a fractional or decimal component. Integers can be positive, negative, or zero. For instance:

These numbers are all integers because they are whole numbers and do not include fractions or decimals.

Q2: How to explain an integer to a child?

You can explain an integer to a child as a whole number that can be positive, negative, or zero. Use real-life examples, such as counting apples (positive integers), temperatures below freezing (negative integers), or having no apples at all (zero).

Q3: What are the three types of integers?

The three types of integers are:

  1. Positive Integers: These are whole numbers greater than zero. Examples include 1, 2, 3, 10, and 100. They are used to represent quantities or counts.
  2. Negative Integers: These are whole numbers less than zero. Examples include -1, -5, -20, and -50. They are used to represent deficits, temperatures below zero, or debts.
  3. Zero: Zero is neither positive nor negative. It represents a neutral value, such as having no items or being at a starting point.

These three types together make up the set of integers, which is essential for understanding basic arithmetic and advanced mathematics.

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