Fraction Commandments
Hill's Fraction Commandments
1.  Thou shalt NEVER add or subtract denominators when adding and subtracting fractions.
2.  Thou shalt ALWAYS multiply the numerator and the denominator when multiplying fractions.
3.  When dividing fractions thou shalt ALWAYS flip the 2nd fraction and multiply.
4.  Thou shalt ALWAYS find a common denominator when adding and subtracting fractions.
5.  To find a common denominator thou shalt ALWAYS find the LCM (Least Common Multiple).
6.  Thou shalt ALWAYS do to the numerator whatever is done to the denominator.