Decimals Review

Here is a quick review on operations with decimals. This video is on subtracting decimals.

Strategy: Before you calculate the exact answer, estimate. Use the estimate to check for the reasonableness of your answer.

Estimate these answers. Then calculate. (Answers are below.)

1. 7.8 + 0.45
2. 45.3 +17.07
3. 32.04 – 7.8
4. 6.3 x 2.4
5. 9.2 / 2.5
6. 12.3 x -3.06
7. -6.3 – 4.2
8. 8.2 – 12.03

Answers:
1. Estimate: 8 Answer = 8.25
2. Estimate: 62 Answer = 62.37
3. Estimate: 24 Answer = 24.24
4. Estimate: 12 Answer = 15.12
5. Estimate: 3 Answer = 3.68
6. Estimate: -36 Answer = -37.638
7. Estimate: -10 Answer = -10.5
8. Estimate: -4 Answer = -3.83

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2 Comments »

  1. Ivy Ryan said

    Period 4 7* I would be glad to do it on the board for the class

    The second You tube video under the catergorie of decimals review helped me to understand the process of borrowing more. Before I hade learned in school that if you can’t borrow from the zero you move on to the next number and work your way back. Although this way works to solve the problem this you tube video taught me that you can include the number before and zero to borrow from them as a whole instead of as individuals. This new idea allowed me to skip over a useless step of decimal subtraction. Here is an example:

    4.59 4.5900 0 is less than 5 but you cant borrow from the next number
    -0.1035 -0.1035 because it is also zero.

    In elementary schoolthey told you to borrow from the 9 and work your way back to the zero. But this new style of combining the 9 and 0 and getting 90 makes the problem a whole lot easier. 8 9 10
    4.5900
    -0.1035
    4.4865 is the answer

  2. Ivy Ryan said

    Period 4 7* I would be glad to do it on the board for the class

    The second You tube video under the category of decimals review helped me to understand the process of borrowing more. Before I hade learned in school that if you can’t borrow from the zero you move on to the next number and work your way back. Although this way works to solve the problem this you tube video taught me that you can include the number before and zero to borrow from them as a whole instead of as individuals. This new idea allowed me to skip over a useless step of decimal subtraction. Here is an example:

    4.59 4.5900 0 is less than 5 but you cant borrow from the next number
    -0.1035 -0.1035 because it is also zero.

    In elementary schoolthey told you to borrow from the 9 and work your way back to the zero. But this new style of combining the 9 and 0 and getting 90 makes the problem a whole lot easier. 8 9 10
    4.5900
    -0.1035
    4.4865 is the answer

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