
Name: Debbie
Who is asking: Student
Level: All
Question:
I have another question please, WHY do we invert and multiply when dividing fractions? I know that's what we do but WHY? What is the reasoning behind it?
Hi again Debbie,
I find it helps to reword a division problem as a multiplication problem.
Reword 

 "What is 15 divided by 5?" 
to  
 "What number, multiplied by 5, gives 15?" 
That is  
 15/5 = ? 
becomes  
 ? x 5 = 15 
Clearly the answer here is 3 since 3 x 5 = 15. 
Similarly with fractions 
 
becomes  
 
Here the answer is  
 
since  
 
The rule "invert and multiply" is just a handy way to say 
 
is 
 
Cheers,
Penny

