Approximate Calculations

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    APPROXIMATE

    CALCULATIONS30503 30507

    30520

    30532

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    WHATIS APPROXIMATE CALCULATION?

    Definition : getting answers from undefinedproblems(some/all conditions are not given)

    Problem solvers have to make some/all of the conditionsto get the answer

    Usually the answers are unable to measure or unknown

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    WHYISITUSEFUL?

    Used in various types of interviews (highschool/companies(eg. Google))

    Can measure ones creativity in solving simplemath problems (no complicated concepts are used,but it is not easy to answer)

    Can measure logical flow of thoughts

    Useful in interviews=useful for your future!

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    EXAMPLEPROBLEM-1Find the weight of an airplane.

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    HOWTO ?

    1. 1. Make expressions to solve the given problem

    2.

    Figure out what conditions are missing

    3. Think what values/conditions could work in those p

    laces

    4. Substitute those made-up values into the expressi

    on

    5. Solve the expression & find the answer

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    THINGSTOREMEMBER

    1. expressions mustbe correct

    2. should find all themissing values/conditions in the problem

    & should satisfy allof them

    3. values should bepossible, but doesnt have to be accurat

    e

    5. there is no correct answer & every an

    swer is correct

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    MAKINGEXPRESSIONS& FINDINGOUTMISSINGCONDITIONS

    wings(2) + fuselage + engines(4) + fuel

    + people in the airplane

    + luggage+ other components in it

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    SPECIFICVALUES/CONDITIONS

    Wing(1) = 7t

    Body part = 35t

    Engine(1)=3t

    Fuel = 1t (From Seoul to New York)

    1 person = 70kg

    Luggage = 15kg per each person

    Other components = 10t

    There are 250 people in the plane

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    SOLVINGTHEEXPRESSIONS

    Weight of an airplane

    =72 + 35 + 34 + 1 + 0.07250

    + 0.015250 + 10 = 93.25(t)

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    EXAMPLE PROBLEMS-2

    How long will it take to

    count ?

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    MAKINGEXPRESSIONS& FINDINGOUTMISSINGCONDITIONS

    (The time that it takes to count one digit number) (the number of one digit numbers)

    (The time that it takes to count a two digit number) (the number of two digit numbers)

    ~

    (The time that takes to count an eight digit number) (the number of eight digit numbers)

    Add them all up, and you will get the answer(assuming that the numbers are read nonstop)

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    SPECIFIC VALUES

    Assume that the time that it takes to read one andtwo digit numbers is one second, three digitnumbers; two seconds, four digit; three seconds

    and so on.

    There are 9 one digit numbers, 90 two digitnumbers, 900 three digit numbers, 9000 four digitnumbers and so on.

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    SOLVINGTHEEXPRESSIONS

    The time it takes to read up to 100000000

    =19 + 190 + 2900 + 39000 + 490000 +5900000 + 69000000 + 790000000

    =688888899seconds= approximately 11481482 minuets

    =191358 hours

    =7973 days

    =266 months=21years

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    RESOURCES

    Not many resources are available]

    Similar concept is used in physics and calculus, so

    you will only find difficult physics and mathproblems if you search this concept

    This concept is often used in interviews of Google,

    so you can search for it and see different kinds ofproblems and good solutions for them

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    GOOGLEINTERVIEW QUESTIONS(RELATEDTOTHISTOPIC)

    1. How many people in San Francisco were on Facebook last Friday 2:30 pm?

    2. How many golf balls will fit in a schoolbus?

    3. How many windows are in Seattle?

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    EXAMPLE PROBLEMS

    1. Find the number of dimples on a golf ball.

    2. find the number of existing ballpoint pen

    s on the world

    3. Find the weight of this school building.

    4. Find the number of candys a person eats during their lifetime