Multiplication and Division Rules (Sign Rules)
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Interactive Audio Lesson
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Introduction to Multiplication and Division Sign Rules
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Today, we are learning about the multiplication and division sign rules. Can anyone tell me what happens when we multiply two positive numbers?
I think it stays positive!
Exactly! Positive multiplied by positive gives us a positive result. Great job! What about multiplying two negative numbers?
That's also positive!
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?
It becomes negative!
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
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Now, letβs look at division. Who can tell me what -15 divided by 3 equals?
Itβs -5!
Exactly, because a negative divided by a positive gives us a negative result! How about if we divide -15 by -3?
That would be positive 5!
Great! So remember, division follows the same sign rules as multiplication: a negative divided by a negative results in a positive.
That makes sense now!
Combining the RulesβPractical Examples
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Letβs solidify our understanding with some examples. What is 4 Γ -2?
Thatβs -8.
Right! Now what about -4 Γ· 2?
-2.
Perfect! Now tell me, whatβs the result of -4 multiplied by -2?
Thatβs 8!
Excellent! So, letβs 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 summaries of the section's main ideas at different levels of detail.
Quick Overview
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:
- Positive Γ Positive = Positive: The product of two positive integers is always positive. For example, 3 Γ 5 = 15.
- Negative Γ Negative = Positive: The product of two negative integers is also positive. For instance, -3 Γ -5 = 15.
- Positive Γ Negative = Negative: The product of a positive and a negative integer results in a negative integer. For instance, 3 Γ -5 = -15.
- Negative Γ Positive = Negative: This is analogous to the previous rule; thus, -3 Γ 5 = -15.
- Division rules mirror multiplication rules: Therefore, similar outcomes are applied for division depending on the signs of the integers involved. For example, 15 Γ· 3 = 5 (positive result), while -15 Γ· 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.
Key Concepts
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Positive Γ Positive = Positive: The product of two positive integers is always positive.
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Negative Γ Negative = Positive: The product of two negative integers is positive.
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Positive Γ Negative = Negative: The product of a positive integer and a negative integer is negative.
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Negative Γ· Positive = Negative: A negative number divided by a positive number is negative.
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Negative Γ· Negative = Positive: A negative number divided by a negative number is positive.
Examples & Applications
3 Γ -5 = -15 (A positive times a negative yields a negative result.)
-6 Γ -2 = 12 (A negative times a negative yields a positive result.)
-20 Γ· 4 = -5 (A negative divided by a positive yields a negative result.)
15 Γ· -3 = -5 (A positive divided by a negative yields a negative result.)
Memory Aids
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Rhymes
When both signs are the same, a positiveβs your gain, / But with one sign thatβs a negative, a negativeβs your bane.
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!
Memory Tools
Remember: Same signs yield a positive, different signs yield a negative. You can think of it as 'Same So Positive, Different So Negative.'
Acronyms
Remember 'P' for Positive, 'N' for Negative, and 'Z' for Zero in multipliers
PP= P
NN= P
PN= N
NP= N.
Flash Cards
Glossary
- Sign Rules
The rules that determine the sign of the product or quotient based on the signs of the numbers being multiplied or divided.
- Positive Integer
An integer greater than zero, e.g. 1, 2, 3.
- Negative Integer
An integer less than zero, e.g. -1, -2, -3.
Reference links
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