## Key Concepts

• Multiplication of Signed Numbers
• To determine the sign of the product of two signed numbers:
Same Signs Product
Two positives

Two negatives

Positive

Positive

Different Signs Product
Positive • negative

Negative • positive

Negative

Negative

• Division of Signed Numbers
• To determine the sign of the quotient of two signed numbers:
Same Signs Quotient
Two positives

Two negatives

Positive

Positive

Different Signs Quotient
Positive • negative

Negative • Positive

Negative

Negative

• Multiplication by $-1$
• Multiplying a number by $-1$ gives its opposite: $-1(a)=-a$
• Division by $-1$
• Dividing a number by $-1$ gives its opposite: $a\div(-1)=-a$