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From Michael Olivero:
Learn how to do mental calculations up to 8 digits x 8 digits. Learn all the steps in the tutorial section and then practice and see how you compare in game center to hundreds of other users who have already learned the technique.Simply choose the difficulty from 2x2 through 4x4 and a special masters level of 8x8 and a random set of numbers appear for you to multiply using the powerful technique of cross multiplying.The application gives you immediate feedback helping you improve your mental multiplication abilities.