Remind Me Why "Invert and Multiply" Works When Dividing Fractions.
© 2008, Agnes Azzolino www.mathnstuff.com/math/spoken/here/2class/70/frwhy.htm |

Resources
Go to DIVIDE AND CONQUER to see notes and resources on fractions, decimals, proportions, and primes. Click on a graphic to see just the graphic. |

The Math You Need to Know
- You chose the format in which to complete the problem.
- Any number multiplied by its
reciprocal (its
multiplicitive inverse) is 1.
- Any number multiplied by 1 is the number.
One is the multiplicative identity .
(a)(1) = a
- Any number divided by one, is that number.
a/1 = a
Another way of saying this is "If 1 is the denominator of a fraction, just use the numerator."
The goal is to make the division expression look like just one number, perhaps a fraction or mixed number, but, still just one number. Multiplying by the reciprocal and multiplying by 1 result in "the product of the first fraction and the reciprocal of the second" -- "copy the first, then, invert and multiply." |