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Exercises: addition and subtraction of decimal numbers

With these exercises, you can practice adding and subtracting decimal numbers. Can you solve them all?

  1. 1

    Add up the following decimal numbers.

    1. 0.44+0.2340.44+0.234

    2. 2.983+0.2302.983+0.230

    3. 9.33+49.33+4


    4. 0.00034+0.0320.00034 + 0.032

    5. 0.983+2.78+11.6730.983 + 2.78 + 11.673

    6. 2.3+3.22.3+3. 2

    7. 22+7.535+0.09322+7.535+0.093

  2. 2

    Subtract the following decimal numbers:

    1. 0.450.290.45-0.29


    2. 0.9650.830.965-0.83


    3. 1.7820.2341.782-0.234


    4. 34.981.06134.98-1.061


    5. 4.9132.9114.913-2.911


    6. 2.0431.9212.043-1.921


    7. 11.6937.77711.693-7.777%


  3. 3

    Subtract the following fractions and decimal numbers

    1. 1.04121.04-\frac{1}{2}

    2. 630.23\frac{6}{3}-0.23

    3. 1.8180.081.8-\frac{1}{8}-0.08

    4. 0.944110.94-\frac{4}{11}

    5. 2.984112.98-\frac{4}{11}

  4. 4

    We consider the following sum: 1+0.1+0.01+0.001+1+0.1+0.01+0.001+\dots

    (Perhaps you already know that 0.2=29,  0.3=39=13,  0.7=790.\overline2=\frac29,\;0.\overline3=\frac39=\frac13,\;0.\overline7=\frac79 and so on.)

    1. What are the three next terms in the sum after 0.0010.001? How are two successive summands related to each other?

    2. Calculate the value of the above sum both as a repeating decimal and as a fraction.

    3. Calculate the value of the difference 30.20.020.0023-0.2-0.02-0.002-… both as a repeating decimal and as a fraction.


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