## 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

- To determine the sign of the product of two signed numbers:
**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

- To determine the sign of the quotient of two signed numbers:
**Multiplication by \(-1\)**- Multiplying a number by \(-1\) gives its opposite: \(-1a=-a\)

**Division by \(-1\)**- Dividing a number by \(-1\) gives its opposite: \(a÷\left(-1\right)=\mathit{\text{−a}}\)