Here is a set of free short videos for stepwise preparation of Number Systems on GMAT. For a more detailed treatment of the topic, you may want to opt for our GMAT online course or our GMAT test series of 15 mock tests.
Classification of Numbers
Some Exceptions on Integers
Even and Odd Integers
Finding Units Digit of a Huge Multiplication
Finding Last Digit of a Large Exponent
Finding the Number of Factors
Finding the Highest Power in a Factorial
Terminating Fractions
How to Find Remainder for a Huge Product
Finding Remainder for a Large Exponent
The Most Favorite Remainder Question Type on GMAT
An Important Surds and Indices Question Type
Another Important Surds and Indices Question Type