| Most pizza places cut pizza into 8 slices like this. | ||||
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| Math people (who really like pizza) | ||||
| wanted a way to talk about slices of pizza. | ||||
| They thought up a way to write how many slices they have | ||||
| and how many slices there are in the whole pizza all at once. | ||||
| The tricky part is the line they used to keep the two numbers apart. | ||||
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| Example: | ||||
| If a pizza is cut into 8 slices, and we have 3 slices, | ||||
| how much of the whole pizza do we have? | ||||
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| OK, Let's look at this another way. | ||||
| Example: | ||||
| Say we have one slice of pizza. | ||||
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| and someone gives us two more. | ||||
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| Could we write that as an addition problem? | ||||
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Sure. |
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| Do it the same way you write any addition problem. | ||||
| Write one thing. | ||||
| Write a plus sign. | ||||
| Write the other thing. | ||||
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| We know the answer to this one. | ||||
| If you start with 1 slice of pizza and get 2 more | ||||
| you have 3 all together. | ||||
| The whole pizza still has 8 slices so all together | ||||
| the problem looks like this: | ||||
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| More Examples: | ||||
| Add 2 slices plus 3 slices from an 8 slice pizza | ||||
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| Add 4 slices plus 2 slices from an 8 slice pizza. | ||||
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| In order for these problems to work, | ||||
| the pizza slices must come from pizzas | ||||
| cut into the same number of slices. | ||||
| On another page we'll talk about what to do | ||||
| when the pizzas have different numbers of slices. | ||||
| Try another one ... | ||||
| Example: | ||||
| Add 5 slices plus 3 slices from an 8 slice pizza. | ||||
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| Look at that one again. | ||||
| We ended up with 8 slices. | ||||
| That means we have 1 whole pizza. | ||||
| So: | ||||
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| How about this ... | ||||
| Example: | ||||
| Say we have 3 slices of pizza. | ||||
| Then we eat one. | ||||
| That's like subtraction isn't it? | ||||
| Sure is! | ||||
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| Pizzas don't always have 8 slices. | ||||
| Some have 12 slices. | ||||
| A slice from one of those pizzas would be: | ||||
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| Say we had one wacky pizza that was cut into only 3 slices. | ||||
| If we had one of those slices, we would have: | ||||
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|
copyright 2005 Bruce Kirkpatrick |
