Math 7A Unit 3 Multiply/Divide Rational Numbers by Ms. Phoebe Saltzstein

Multiplying and Dividing Rational Numbers

phoebesaltzstein — 2025-09-02 16:24:36 UTC

All the rules and procedures in one place! Thanks to Mrs. Angell for this great reference.

When do we need to multiply negative fractions and decimals?

phoebesaltzstein — 2025-09-02 16:35:35 UTC

1. A temperature decrease would be represented by a negative decimal like a drop of 1.6 degrees. If that was the drop every hour, we could multiply -1.6 times the number of hours.

2. Next year and in Algebra 1 you will learn about the slope of a line. The line's slope (or slantyness) will be measured as a fraction (rise over run) and it will frequently be negative! There will be problems that require you to multiply the slope by the x coordinate to find the y coordinate.

3. Debts are represented with negative numbers, and they are frequently decimals like -$25.89

How to Cross Cancel Fractions that are being Multiplied

phoebesaltzstein — 2025-09-02 16:38:45 UTC

Basically, this is simplifying the fractions before you mutliply. Dividing a common factor out of the numerator and denominator.

phoebesaltzstein — 2025-09-02 18:34:41 UTC

phoebesaltzstein — 2025-09-02 18:35:23 UTC

phoebesaltzstein — 2025-09-02 18:36:03 UTC

Example of Dividing Rational Numbers

phoebesaltzstein — 2025-09-04 16:47:15 UTC