Khan Academy Videos

Greatest Common Divisor (GCD)
http://www.khanacademy.org/video/greatest-common-divisor?playlist=Arithmetic

Least Common Multiple (LCM)
http://www.khanacademy.org/video/least-common-multiple?playlist=Arithmetic

Adding Decimals
http://www.khanacademy.org/video/adding-decimals?playlist=Arithmetic

Subtracting Decimals
http://www.khanacademy.org/video/subtracting-decimals?playlist=Arithmetic

Multiplying
http://www.khanacademy.org/video/multiplication-6--multiple-digit-numbers?playlist=Arithmetic

Multiplying (Lattice strategy)
http://www.khanacademy.org/video/lattice-multiplication?playlist=Arithmetic

Long Division
http://www.khanacademy.org/video/division-2?playlist=Arithmetic

Negative Numbers Introduction
http://www.khanacademy.org/video/negative-numbers-introduction?playlist=Pre-algebra

Adding and Subtracting Negative Numbers
http://www.khanacademy.org/video/adding-subtracting-negative-numbers?playlist=Pre-algebra

Multiplying and dividing negative numbers
http://www.khanacademy.org/video/multiplying-and-dividing-negative-numbers?playlist=Pre-algebra

Equivalent Fractions
http://www.khanacademy.org/video/equivalent-fractions?playlist=Arithmetic

Mix Numbers and Improper Numbers
http://www.khanacademy.org/video/mixed-numbers-and-improper-fractions?playlist=Arithmetic

Converting Fractions to Decimals
http://www.khanacademy.org/video/converting-fractions-to-decimals?playlist=Arithmetic

Adding and subtracting fractions
http://www.khanacademy.org/video/adding-and-subtracting-fractions?playlist=Pre-algebra

Multiplying Fractions
http://www.khanacademy.org/video/multiplying-fractions?playlist=Pre-algebra

Dividing Fractions
http://www.khanacademy.org/video/dividing-fractions?playlist=Pre-algebra

Order of Operations
http://www.khanacademy.org/video/introduction-to-order-of-operations?playlist=Pre-algebra

More complicated Order of Operations
http://www.khanacademy.org/video/more-complicated-order-of-operations-example?playlist=Pre-algebra

Ratios as Fractions in Simplest Form
http://www.khanacademy.org/video/ratios-as-fractions-in-simplest-form?playlist=Developmental%20Math

Simplifying Rates and Ratios
http://www.khanacademy.org/video/simplifying-rates-and-ratios?playlist=Developmental%20Math

Understanding Proportions
http://www.khanacademy.org/video/understanding-proportions?playlist=Developmental%20Math

Finding an Unknown in a Proportion
http://www.khanacademy.org/video/find-an-unknown-in-a-proportion?playlist=Developmental%20Math

Representing a number as a decimal, percent, and fraction
http://www.khanacademy.org/video/representing-a-number-as-a-decimal--percent--and-fraction?playlist=Developmental%20Math