Subtracting Whole Numbers: Subtraction Problems May Not Be Rearranged
This clip explains that, while the addends can be rearranged or regrouped in addition without affecting the answer, the same is not true in subtraction.
Subtracting Whole Numbers: Using the Addition Facts in Subtraction
This clip makes the case that "since every subtraction fact is an addition fact in disguise, learning them isn't so hard."
Subtracting Whole Numbers: Using Addition to Check Your Answers
This clip explains how addition can be used to verify that the answer to a subtraction problem is correct.
Dividing Whole Numbers, Part 2: Partial Quotients and Multiples of Ten
This clip explains how understanding and learning powers of ten and learning multiples of ten can reduce the number of partial quotients needed to solve a division problem.
Associative Law for Addition
The associative law for addition: (a b) c = a (b c).
Adding More Complex Expressions
Demonstration of adding terms in a complex algebraic expression and a practical problem demonstrating application of this skill in the real world.
Adding Rational Numbers with Different Denominators
In order to add or subtract rational expressions with different denominators, the least common denominator must be found and the fractions rewritten with the same denominator.
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 Rational Expressions with Different Denominators
Rational expressions with different denominators are added and the procedure explained.
Adding and Subtracting Rational Expressions
The rules for adding and subtracting rational expressions are similar to those for adding and subtracting rational numbers, beginning with the rule that in order to be added, rational numbers must have the same denominator. Addition examples are dem...