Basic number

The links to these instructional YouTube clips come from The Organic Chemistry Tutor.

Order of operations [length: 15m:51s]
This video provides a basic introduction into order of operations. (Sometimes referred to as BEDMAS or PEMDAS). 

Addition and subtraction [length: 12m:13s]
This video details the process of addition and subtraction of positive and negative numbers using a number line. 

Multiplying and dividing [length: 11m:39s]
This video details a basic introduction into multiplying and dividing numbers. It explains how to perform basic multiplication by hand as well as long division. 

Finding greatest common factor [length: 10:28s]
This video details how to find the greatest common factor or two or 3 numbers.

 Prime factorisation [length: 11m:28s]
This video  explains the difference between prime and composite numbers.  It discusses how to write the prime factorisation of large numbers. 

Multiplying integers [length: 11m:11s]
This video explains how to multiply integers with different signs and how to multiply negative integers and large integers as well.  

Multiplying decimals made easy [length: 10m:31s]
This video explains how to simplify surds (or radicals) It covers plenty of examples and practice problems simplifying square roots with fractions, adding and subtracting radicals, as well as dividing radical expressions. 

Surd simplification [length: 13m:13s]
This video details how to multiply algebraic fractions. 

Number series [length: 14m:43s]
This video explains how to find the next term in a number series. It provides plenty of examples of finding patterns in arithmetic and geometric sequences.