3.17小数加法

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  小数加法

  

  [Figure 1]

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  Yoshi and his family have decided to have a yard sale. Yoshi's mother has him collect all the money from the customers. Yoshi wants to make sure that he is collecting the right  amount  from each person. The first person buys one item for $12.25, a second item for $0.50 and a third item for $0.75. Yoshi knows that he needs to add the decimals but isn't sure how to begin. How much money does the first person owe Yoshi?
  ::Yoshi的母亲要他从顾客那里收集所有的钱。 Yoshi希望确保他从每个人那里收集到正确的金额。第一个人购买一件12.25美元,第二个0.50美元,第三个0.75美元。Yoshi知道他需要加上小数,但不知道如何开始。第一个人欠Yoshi多少钱?

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  In this concept, you will learn how to add decimals. 
  ::在此概念中,您将学习如何添加小数。

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  Adding Decimals
  ::添加十进数

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  To add decimals, work with the wholes and parts of the numbers separately. Add the parts then add the wholes.
  ::要添加小数点,请分别使用数字的整数和部分。添加部件,然后添加整数。

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  The best way to do this is to keep the parts together and keep the wholes together.
  ::最好的办法就是把部件放在一起 整件事都放在一起

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  To do this, simply line up the decimal points in each number that you are adding.
  ::为此,只需在您正在添加的每个数字中直线排列小数点。

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  Let's look at an example.
  ::让我们举个例子。

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  Add 3.45 + 2.37 = _____
  ::加3.45+2.37=____

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  In this problem you have parts and wholes. Let’s rewrite the problem vertically, lining up the decimal points.
  ::在此问题上,您有部分和整体。让我们垂直重写问题,将小数点排成一行。

  $$\begin{array}{r}3.45\\ \underset{\_}{+2.37}\end{array}$$

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  Next, add the columns vertically and bring the  decimal point  down into the answer of the problem.
  ::下一步,垂直添加列,并将小数点移到问题的答案中。

  $$\begin{array}{r}3.45\\ \underset{\_}{+2.37}\\ 5.82\end{array}$$

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  The answer is 5.82.
  ::答案是5.82。

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  Let's look at another example.
  ::让我们再举一个例子。

  5 + 3.45 + 0.56 = _______

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  In a problem like this, line up the decimal points, but add zeros to help hold places where there aren’t numbers. This helps keep the addition straight.
  ::在这样的问题中, 将小数点排成一行, 但添加零来帮助保持没有数字的位置。 这有助于保持添加的直线 。

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  First, line up the problem vertically.
  ::首先,垂直排列问题。

   

  $$\begin{array}{r}5.00\\ 3.45\\ \underset{\_}{+0.56}\end{array}$$

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  Notice that zeros help hold places where you did not have numbers. Now each number in the problem has the same number of digits.
  ::请注意, 零帮助保留您没有数字的位置。 现在问题中的每个数字的数字相同 。

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  Add the numbers.
  ::添加数字。

  $$\begin{array}{r}5.00\\ 3.45\\ \underset{\_}{+0.56}\\ 9.01\end{array}$$

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  The answer is 9.01.
  ::答案是9.01。

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  Try it yourself!
  ::你自己试试看!

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  Examples
  ::实例

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  Example 1
  ::例1

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  Earlier, you were given a problem about Yoshi and the yard sale.
  ::早些时,你被问及 吉吉和院子销售的问题。

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  Yoshi's first customer wants to buy 3 different things.  To ask for the correct total amount, Yoshi needs to add $12.25, $0.50 and $0.75.  Can you find the total amount due?
  ::Yoshi的第一个客户想买3种不同的物品。为了要求正确的总额,Yoshi需要加上12.25、0.50和0.75美元。你能找到到期的总额吗?

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  First, line up the numbers vertically.
  ::首先,垂直排列数字。

  $$\begin{array}{r}12.25\\ 0.50\\ \underset{\_}{+0.75}\end{array}$$

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  Then, add the numbers.
  ::然后加上数字。

  $$\begin{array}{r}13.50\end{array}$$

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  The answer is $13.50. Yoshi must collect $13.50 from the customer.
  ::答案是13.50,Yoshi必须向顾客收取13.50美元。

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  Example 2
  ::例2

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  Add the following numbers.
  ::添加以下数字。

  13.25 + 0.80 + 1.30  = _____

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  First, line up the numbers vertically.
  ::首先,垂直排列数字。

  $$\begin{array}{r}13.25\\ 0.80\\ \underset{\_}{+1.30}\end{array}$$

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  Then, add the numbers.
  ::然后加上数字。

  $$\begin{array}{r}15.35\end{array}$$

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  The answer is 15.35.
  ::答案是15.35。

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  Example 3
  ::例3

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  Add the following decimals.
  ::添加以下小数。

  4.56 + 0.89 + 2.31 = _____

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  First, line up the numbers vertically.
  ::首先,垂直排列数字。

   

  $$\begin{array}{r}4.56\\ 0.89\\ \underset{\_}{+2.31}\end{array}$$

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  Then, add the numbers.
  ::然后加上数字。

  $$\begin{array}{r}7.76\end{array}$$

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  The answer is 7.76.
  ::答案是7.76

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  Example 4
  ::例4

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  Add the following decimals.
  ::添加以下小数。

  5.67 + 0.65 + 0.93 =_____

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  First, line up the numbers vertically.
  ::首先,垂直排列数字。

     

  $$\begin{array}{r}5.67\\ 0.65\\ \underset{\_}{+0.93}\end{array}$$

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  Then, add the numbers.
  ::然后加上数字。

  $$\begin{array}{r}7.25\end{array}$$

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  The answer is 7.25.
  ::答案是7.25。

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  Example 5
  ::例5

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  Add the following decimals.
  ::添加以下小数。

  88.92 + 0.57 + 3.12 = _____

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  First, line up the numbers vertically.
  ::首先,垂直排列数字。

  $$\begin{array}{r}88.92\\ 0.57\\ \underset{\_}{+3.12}\end{array}$$

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  Then, add the numbers.
  ::然后加上数字。

  $$\begin{array}{r}92.61\end{array}$$

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  The answer is 92.61.
  ::答案是92.61。

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  Keep practicing on your own!
  ::继续自己练习!

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  Review
  ::回顾

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  Add the following decimals.
  ::添加以下小数。

  1. 4.5 + 6.7 = _____
  2. 3.45 + 2.1 = _____
  3. 6.78 + 2.11 = _____
  4. 5.56 + 3.02 = _____
  5. 7.08 + 11.9 = _____
  6. 1.24 + 6.5 = _____
  7. 3.45 + .56 = _____
  8. 87.6 + 98.76 = _____
  9. 76.43 + 12.34 = _____
  10. 5 + 17.21 = _____
  11. 78 + 13.456 = _____
  12. .456 + .23 + .97 = _____
  13. 1.234 + 4.5 + 6.007 = _____
  14. 3.045 + 3.3 + 9 = _____
  15. 23 + 4.56 + .0091 = _____

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  Review (Answers) 
  ::回顾(答复)

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  Click   to see the answer key or go to the Table of Contents and click on the Answer Key under the 'Other Versions' option.
  ::单击可查看答题键, 或转到目录中, 单击“ 其他版本” 选项下的答题键 。

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  Resources
  ::资源