Math 7 · Unit 3, Lesson 4
Multiplying Signed Numbers
Multiplying with negative numbers
ElleMath-speak
In this lesson, we multiply signed numbers. Multiplication is repeated addition, so the rules for adding signed numbers tell us what the answer must be.
FinnPlain English
Times means groups of. Three groups of a four dollar debt is a twelve dollar debt. Once you see why, the sign rules make sense.
Write it down. Do every change on paper, one line per step. Changing signs in your head is the number one reason for missed problems. If you changed something, it should be on the paper.
Go in order. Each tile has a short explanation, then a "Let me try a few" button.
1Debts Over and OverA negative times a positiveStart here
2Negative Times NegativeTaking away debts makes you richer
3Count the NegativesLong problems, fractions, and decimals
4Real-World ProductsTemperatures, dives, and money over time
When you have finished
At the end of each tile you will find a review form to give us feedback.
NC standard: NC.7.NS.2.