2.2.1.4 - Multiplication and Division Rules (Sign Rules)

You've not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take mock test.

Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Introduction to Multiplication and Division Sign Rules

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Today, we are learning about the multiplication and division sign rules. Can anyone tell me what happens when we multiply two positive numbers?

Student 1
Student 1

I think it stays positive!

Teacher
Teacher

Exactly! Positive multiplied by positive gives us a positive result. Great job! What about multiplying two negative numbers?

Student 2
Student 2

That's also positive!

Teacher
Teacher

Right again! So, remembering that positive times positive equals positive and negative times negative equals positive is key. What about mixing signs, like a positive and a negative?

Student 3
Student 3

It becomes negative!

Teacher
Teacher

Correct! Now, let's summarize: if one number is negative and the other is positive, we get a negative product.

Application of Sign Rules in Division

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Now, letโ€™s look at division. Who can tell me what -15 divided by 3 equals?

Student 4
Student 4

Itโ€™s -5!

Teacher
Teacher

Exactly, because a negative divided by a positive gives us a negative result! How about if we divide -15 by -3?

Student 1
Student 1

That would be positive 5!

Teacher
Teacher

Great! So remember, division follows the same sign rules as multiplication: a negative divided by a negative results in a positive.

Student 2
Student 2

That makes sense now!

Combining the Rulesโ€”Practical Examples

Unlock Audio Lesson

Signup and Enroll to the course for listening the Audio Lesson

0:00
Teacher
Teacher

Letโ€™s solidify our understanding with some examples. What is 4 ร— -2?

Student 3
Student 3

Thatโ€™s -8.

Teacher
Teacher

Right! Now what about -4 รท 2?

Student 4
Student 4

-2.

Teacher
Teacher

Perfect! Now tell me, whatโ€™s the result of -4 multiplied by -2?

Student 1
Student 1

Thatโ€™s 8!

Teacher
Teacher

Excellent! So, letโ€™s summarize our findings: the sign rules apply consistently for both multiplication and division. Positive times positive is positive, negative times negative is positive, and a mix leads to negative.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section covers the rules for multiplying and dividing integers with a focus on the signs of the numbers involved.

Standard

The section explains the sign rules for multiplication and division of integers, emphasizing how the signs of the numbers affect the outcomes. It includes the essential principles that govern the multiplication and division of both positive and negative integers.

Detailed

Multiplication and Division Rules (Sign Rules)

Understanding the rules of multiplication and division is essential for achieving fluency in number operations. The rules governing the signs of integers during multiplication and division state:

  1. Positive ร— Positive = Positive: The product of two positive integers is always positive. For example, 3 ร— 5 = 15.
  2. Negative ร— Negative = Positive: The product of two negative integers is also positive. For instance, -3 ร— -5 = 15.
  3. Positive ร— Negative = Negative: The product of a positive and a negative integer results in a negative integer. For instance, 3 ร— -5 = -15.
  4. Negative ร— Positive = Negative: This is analogous to the previous rule; thus, -3 ร— 5 = -15.
  5. Division rules mirror multiplication rules: Therefore, similar outcomes are applied for division depending on the signs of the integers involved. For example, 15 รท 3 = 5 (positive result), while -15 รท 3 = -5 (negative result).

The comprehension of these sign rules is not just a theoretical exercise; it plays a crucial role in solving real-world problems that involve positive and negative quantities.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Positive ร— Positive = Positive: The product of two positive integers is always positive.

  • Negative ร— Negative = Positive: The product of two negative integers is positive.

  • Positive ร— Negative = Negative: The product of a positive integer and a negative integer is negative.

  • Negative รท Positive = Negative: A negative number divided by a positive number is negative.

  • Negative รท Negative = Positive: A negative number divided by a negative number is positive.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • 3 ร— -5 = -15 (A positive times a negative yields a negative result.)

  • -6 ร— -2 = 12 (A negative times a negative yields a positive result.)

  • -20 รท 4 = -5 (A negative divided by a positive yields a negative result.)

  • 15 รท -3 = -5 (A positive divided by a negative yields a negative result.)

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

๐ŸŽต Rhymes Time

  • When both signs are the same, a positiveโ€™s your gain, / But with one sign thatโ€™s a negative, a negativeโ€™s your bane.

๐Ÿ“– Fascinating Stories

  • Imagine a knight with two shields: one is bright and shining (positive), while the other is dark and gloomy (negative). When two knights with bright shields fight, they shine brighter than ever. But when one dark knight faces a bright one, darkness wins!

๐Ÿง  Other Memory Gems

  • Remember: Same signs yield a positive, different signs yield a negative. You can think of it as 'Same So Positive, Different So Negative.'

๐ŸŽฏ Super Acronyms

Remember 'P' for Positive, 'N' for Negative, and 'Z' for Zero in multipliers

  • PP= P
  • NN= P
  • PN= N
  • NP= N.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Sign Rules

    Definition:

    The rules that determine the sign of the product or quotient based on the signs of the numbers being multiplied or divided.

  • Term: Positive Integer

    Definition:

    An integer greater than zero, e.g. 1, 2, 3.

  • Term: Negative Integer

    Definition:

    An integer less than zero, e.g. -1, -2, -3.