Multiplying Signed Numbers: Multiplying Negative Numbers by Positive Numbers
This clip explains that, as when multiplying whole numbers, we can re-arrange the factors as much as we like when multiplying signed numbers. This enables us to solve multiplication problems in which the first factor is negative and the second posit...
Multiplying Signed Numbers: Multiplying Positive Numbers by Negative Numbers
This clip explains that, to multiply a positive number and a negative number, "
multiply their absolute values and use the negative sign."
Multiplying Signed Numbers: Multiplying Two Numbers With Different Signs
This clip explains that, to multiply two numbers of different signs, in whatever order, "
first, multiply their absolute values, and then use the negative sign. We don't care which comes first, the positive number or the negative number."
Multiplying Signed Numbers: Multiplying Negative Numbers by Negative Numbers
This clip explains that when a negative number is multiplied by another negative number, the product is actually positive.
Multiplying Signed Numbers: Second Exercise in Multiplying Signed Numbers
In this clip, the student utilizes rules taught in the lesson's previous clips to solve problems involving multiplication of signed numbers.
Multiplying Signed Numbers: Multiplication by Negative 1
This clip explains that, "sometimes, in mathematics you want to change the sign. Then it's useful to remember that to do it, just multiply by negative 1. Whatever the original sign might have been, the new one will be the opposite."
Multiplying Signed Numbers: Summary: Multiplying Signed Numbers
This clip reviews the basic rules that apply to multiplying signed numbers. If the two signs are the same, the answer is positive. If they're different, the answer is negative. And, when multiplying more than two signed numbers, if there's an even n...
Multiplying Signed Numbers: General Rule for Multiplying Signed Numbers
This clip explains that if two factors with the same sign are multiplied, the product is always positive. When two factors with different signs are multiplied, the product is always negative.
Multiplying Signed Numbers: Multiplying Three or More Signed Numbers
This clip explains that, when multiplying three or more signed numbers, if the number of negative factors is even, the product is positive. If it's odd, the product is negative.
Multiplying Signed Numbers: Third Exercise in Multiplying Signed Numbers
This clip provides the student with additional exercises in multiplying signed numbers. The clip notes that, "
choosing the right sign is particularly important."