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: Borrowing
This clip uses expanded notation to demonstrate the technique known as borrowing in subtracting both two and three-digit numbers.
Subtracting Whole Numbers: Using Columns to Subtract Two-Digit Numbers
This clip explains the use of columns when doing subtraction problems with "larger numbers." With this approach, we subtract "ones from ones, tens from tens (and), hundreds from hundreds."
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 1: Summary: Dividing Whole Numbers, Part One
This clip summarizes the key points in Part 1 of Dividing Whole Numbers, including the introduction of the terms dividend, divisor and quotient. It then explains that division was introduced in two different ways: as a shortcut for repeated subtract...
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.
Dividing Whole Numbers, Part 2: Comparing Methods of Division
This clip explains that dividing can sometimes be done more quickly for those comfortable with guessing the partial quotient rather than figuring it out. On the other hand, the method known as "long division" offers another approach altogether.
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 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...
Additive and Multiplicative Inverses
Every number except zero has a multiplicative inverse. An explanation of multiplicative inverses and their usefulness in solving algebraic equations.