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B Decimal computation by hand

  1. Jun 17, 2016 #1
    I have to perform the following computation by hand to get a number within two decimal places:
    ##\displaystyle (120)(\frac{54.30}{194.79})##. The answer is 33.45, but how can I do this by hand?
  2. jcsd
  3. Jun 17, 2016 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Well, the multiplication part should be easy enough. It's the long division which takes a bit more effort.

    Remember, $$a ⋅ \frac{b}{c} = \frac{a ⋅ b}{c}$$

    Don't tell me you've never done any arithmetic by hand.
  4. Jun 17, 2016 #3


    Staff: Mentor

    multiply top and bottom by 1 ie 100/100 to get 120 * 5430/19479

    next use long division

    You could first multiply the numerator by 120 before you divide
  5. Jun 17, 2016 #4
    Okay, so doing the long division ##\frac{651600}{19479}## I can get to 33, but then I have the remainder ##\frac{8793}{19479}##. How can I figure out that this remainder is approximately 0.45?
  6. Jun 17, 2016 #5


    Staff: Mentor

    Have you forgotten how to do long division?

    Here's an example image:

  7. Jun 17, 2016 #6


    Staff: Mentor

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