The Singing Hedgehog Guide to:
Subtracting Fractions 2

Subtracting with mixed numbers is normally just the same as adding.

The only problem comes when the second fraction is smaller.

Here is an example of this sort of take away sum.

 Write out the question
 
 
 Subtract the whole numbers
 Put down the LCM

 

 Do the "Not thinking very much at all" line

 Work out what has happened to the bottoms

 Do the same to the top as we did to the bottom

 Write in the top values
 
 

Now we're in trouble!

All we do is the same as for a normal take away question and borrow.

We steal a whole one from the three but because we are doing fifteenths
that whole one becomes 15 fifteenths:



Now we can complete the question:

 Borrow from the 3
 Add the 15 fifteenths to the 3 that are already there



 Take away the tops

 Don't subtract the bottoms!



fractions index

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