Dividing Rational Numbers Pre-Algebra

Vocabulary Rational Number: Any number that can be written as a fraction. Reciprocal/Multiplicative Inverse: Two numbers whose product is 1. (Switch the numerator and the denominator.)

Example: In order to divide fractions, just remember Kentucky Chicken Fried. K – Keep the first fraction the same C – Change the division to multiplication F – Flip the second fraction (take the reciprocal)

We keep the first fraction in our problem. We change the division to multiplication. We flip the second fraction by taking the reciprocal.

Now we multiply. Since 5 and 15 share a factor of 5, we may factor out 5 from our problem. Since 24 and 36 share a factor of 12, we may factor out 12 from our problem. We multiply across horizontally. Finally, we simplify if necessary.

Example #2: This time we must change our mixed numbers into improper fractions! First we multiply 3 and 2 which yields 6. Then we add 1 to 6 and get 7. First we multiply 9 and 5 which yields 45. Then we add 4 to 45 and get 49.

Our new problem is now: We now use Keep, Change, Flip (KCF) to divide. K CF We factor. And finally, we multiply.