Also, my DD learned the facts in a snap but loves all the "tricks" that are out there. She just finds them cool, and is always trying to find her own. This could be an approach--a little tag to hang your memory hat on. (Eg, if you know that the digits in all numbers divisible by 9 must add to 9, you might more quickly remember that 8 x 9 is 72, not 75.)