Dear Lois Terms:
How do you add fractions?
Mixed-up Marcie
Dear Mixed-Up Marcie:
If you want to learn to add fractions, you'll have to run down to your local pizza parlor and talk to the owner, Joe. For example, suppose you and you friends decide to have an instant pizza party. You run down to Joe's Pizza Palace and say to Joe, "Quick! Give me all the pizza you've got!"
Joe checks his pizza and says," I've got 5/6 of a Pepperoni Pizzazz pizza, 1/2 of a 'No Cheese Please' pizza, and 1/3 of a Mango and Ham pizza.
"But how much pizza is that?" you ask, puzzled.
"Let's see, I guess we'll have to add it up," Joe says, setting the pizza pans up on the counter. He writes the problem down on a slip of paper.
You look at the pizza and the problem and here is what you see:
"The first thing we have to do is get these pizzas cut up into the same size pieces," Joe says. He scribbles a strange list of numbers on the slip of paper.
"Hmm-m-m-m," you think, "Those numbers look like what my math teacher calls multiples".
"Ah, ha!" Joe exclaims, "I see that 6 is our Least Common Multiple or Least Common Denominator, whichever you want to call it. We'll just cut these pizzas up into sixths."
First, Joe changes the problem on the paper to look like this:
Then Joe takes out his supersonic pizza wheel and cuts all three pizzas into sixths.
"Now, we can just count the number of sixths we have," Joe says. "Let's see, one, two, three, four, five, six, seven, eight, nine, ten...ten sixths. Count them for yourself."
Joe writes: 10/6 under the problem.
You stare at the 10/6 of pizza in front of you. "But...But...But what am I going to do with all those pieces?" you cry. "I mean, how many real pizzas is that?"
"Oh," Joe says, "you want to know how many whole pizzas you have. Then we'll have to put all these pieces together." Joe does some scratching on the slip of paper.
Joe changes the problem to look like this:
Then Joe fits the slices of Mango and Ham pizza in with the PepperoniPizzazz and the "No Cheese Please."
Now, Joe gets out his super-hot pizza glue gun and glues six slices together into a whole pizza.
"And, if you want those extra slices in lowest terms, I'll be glad to do that, too," Joe offers. He does some more scratching on the paper.
He changes the problem to look like this:
Then he glues the extra pieces together to make 2/3.
"Thanks!" you say to Joe. "This'll be great!
You pay Joe for the pizza, and he packages your order up in a special "hot delivery" box.
"Have a great party!" Joe calls as you run out the door.
So, there you have it, Marcie -- how to add fractions. Write and let me know how it goes.
Love,
Lois
Read about "The Rules for Integers."
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