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Money Is a Special Decimal

Some rules will change a bit when you start learning about multiplication, but for addition and subtraction, money is really easy. All money is a decimal value with two places. You will see examples including $1.25, $65.98, and $26.34. No matter how big the value gets, you can only have two decimal places. One cent is 0.01. You can't give someone less than one cent if you hand them bills and coins.

There are values less than a cent when you start figuring out tax or interest. But when you look at the money in your pocket, one penny is the smallest amount. We have a numbers tutorial if you want to learn more about decimals and money.

Bring on Some Addition

Let's try one example. You know about adding harder decimals than these, so it shouldn't be a problem.

Question:
Timmy runs down the street to buy some fruit. He picks out two apples that cost forty-five cents each and 3 oranges that cost eighty cents each. How much does he pay in total?
Steps to Solve:
0.45+0.45+0.80+0.80+0.80=?
We can group them and solve.
(.45+.45) + (.8+.8+.8) = .9 + 2.4 = 3.3
Answer:
Timmy owes $3.30 for his fruit.

Remember that even though our decimal answer didn't have a zero on the end, when you write out values for money, you always need two places to the right of the decimal point. You can't write that something costs $16.7 dollars. You should write $16.70 so people understand what you mean. Let's do one more...

Question:
Helen was having a party for three friends. One wanted a cupcake for $2.55, one wanted a hot dog for $1.20, and one wanted a piece of pizza for $1.25. How much did Helen pay for lunch?
Steps to Solve:
2.55+1.20+1.25=?

Let's look at this one in a stacked layout.

2.55 1.20 + 1.25 ?

• You'll need to carry a little, but it's an easy problem with an answer of 5.00.
Answer:
Helen paid $5.00 for lunch.

If this were a science experiment and those were values of data or measurements of weight, you might write down 5.0. The two decimal places are very important for money. If you have a bunch of zeros at the end of your number in science, you don't have to write them all.

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