Subtracting Signed Numbers: Using the Number Line to Subtract Signed Numbers
This clip explains how students can use the number line to more easily understand the subtraction of negative numbers. The clip also points out that one of the reasons signed numbers were invented "
(was so that) we can subtract any two numbers
la...
Adding Signed Numbers: Adding More Than Two Signed Numbers
This clip explains that the best way to proceed when adding more than two signed numbers is to add all the positive addends and all the negative addends separately, then add the resulting sums.
Adding Signed Numbers: Practical Problems: Temperature and Distance
This clip provides two short exercises, one dealing with temperature changes, the other with changes in direction, to illustrate how to solve practical problems involving the addition of signed numbers.
Adding Signed Numbers: Using Parentheses in Adding Signed Numbers
This clip explains the use of parentheses to eliminate the confusion that might arise if two signs are written next to each other, as when adding a negative number. The clip notes that we don't run into this problem with positive numbers, because in...
Adding Signed Numbers: Summary: Adding Signed Numbers
This clip summarizes how to add signed numbers. It reviews two important rules, one pertaining to addition when the addends have the same sign, the other to addition when the addends have different signs. The clip also revisits the addition of 3 or ...
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."
Multiplying Signed Numbers: Other Ways of Indicating Multiplication by Signed Numbers
This clip explains that signs can sometimes be confused with orders to add or subtract. To avoid this, signed numbers are sometimes enclosed in parentheses. And, in some instances, if both factors are in parentheses, "
we sometimes leave out the mu...
Multiplying Signed Numbers: Fourth Exercise in Multiplying Signed Numbers
This clip provides the student with a few final exercises in multiplying signed numbers. It notes that, "
if you made any mistakes
you can't do much with multiplying signed numbers if you forgot ordinary multiplication."