Khan Academy: Arithmetic and Pre Algebra: Adding Integers With Different Signs

This video shows how to add three fractions, one of which has a negative sign. Practice problems are available. [6:22]

This video shows how to add positive and negative money amounts in the context of a word problem using a number line. Practice problems are available. [3:15]

A video explaining the meaning of exponents and exponential notation. Practice problems are available. [9:46]

This video introduces and explains the concept of ratios through a number of examples. Practice problems are available. [14:13]

This video shows how to plot fractions, negative numbers, decimals, and fractions on a number line. Practice problems are available. [1:58]

This video demonstrates how to find the base number when given a percentage and amount. Practice problems are available. [6:17]

This video shows how to find a unit rate in the context of a word problem. Practice problems are available. [2:31]

This video shows addition of negative numbers on a number line, using absolute values. Practice problems are included. [5:41]

This video explains the associative law of addition by writing an expression in a different way. Practice problems are available. [2:10]

This video showing more examples of long division problems involving single-digit divisors with remainders. Practice problems are available. [10:07]