For more details go to www.abellna.com website. br br A full mental math video may contain 2-8 examples. Only some examples are provided in a given video for demonstration purposes. br br This technique is specific to certain types of fractions. Using the lowest common denominator is not needed. br br 12 + 18 br 17 + 115 br 16 + 113 br br Of course techniques for adding any type of fractions are also included in the Mental Math: Unleash The Power e-book. Some are provided in the video tutorials along with the local website.