Harvard Entrance Exams || No Calculator Allowed 📵

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  • Опубликовано: 29 ноя 2024

Комментарии • 84

  • @jojojo7333
    @jojojo7333 Месяц назад +19

    37449 in 1 minute. 1 + 8 + 64 + 8^3 ( 1 + 8 + 64 ) = 73 + 8^3*73 = 73+73*64*8 = 73 ( 1+512 ) = 73 * 513. Take a sheet of paper = 37449.

    • @henrykoplien1007
      @henrykoplien1007 Месяц назад

      Exactly.

    • @Kwalliteht
      @Kwalliteht Месяц назад +2

      If you add step by step from left to right you even don't need paper.

    • @frankklemm1471
      @frankklemm1471 Месяц назад

      8^5 + 8^4 + 8^3 + 8^2 + 8^1 + 8^0 = (8 + 1) (4096 + 64 + 1) = 9 * 4161 = 41610 - 4161 = 37449

    • @andryvokubadra2644
      @andryvokubadra2644 Месяц назад

      73 x 513 hanya kurang dari 60 detik? Jika sekelas anak SMA, brilian 😂😂😂

    • @FrankStanley-j5y
      @FrankStanley-j5y Месяц назад +2

      Not very elegant, but effective, and not long-winded.

  • @christophernodurft1868
    @christophernodurft1868 Месяц назад +9

    How about just (8^6 - 1)/(8 - 1) = (262144 - 1)/7 = 262143/7 = 37449.
    If you can't readily calculate 8^6, then (8^6 - 1)/7 = (8^3 - 1)(8^3 + 1)/7 = (512 - 1)(512 + 1)/7 = (511 × 513)/7 = 513 × (511/7) = 513 × 73 = 37449.

  • @HansBezemer
    @HansBezemer Месяц назад +6

    Convert all '8's to 2^3. That gives a pattern of 2^15+2^12+2^9+2^6+2^3+1 or (in binary): 1001001001001001. Since all values are 16 bit, every CS student knows them by heart: 32768+4196+512+64+8+1. That's doable.

    • @BaldurNorddahl
      @BaldurNorddahl Месяц назад +3

      We do indeed know at a glance that it is 4096 not 4196 😅

    • @HansBezemer
      @HansBezemer Месяц назад

      @BaldurNorddahl Touché - good catch!!

  • @JeremyDixon1968
    @JeremyDixon1968 Месяц назад +7

    It's 1001001001001001 in base 2 Easy.

  • @guyhoghton399
    @guyhoghton399 Месяц назад +10

    Sum of a G.P. : a(rⁿ - 1)/(r - 1)
    a = First term = 1
    r = common ratio = 8
    n = number of terms
    1.(8⁶ - 1)/(8 - 1)
    = (2¹⁸ - 1)/7
    = 37,449

    • @andryvokubadra2644
      @andryvokubadra2644 Месяц назад

      @@guyhoghton399 how long do you calculate 2^18? 🤔🤔🤔

    • @jimwong7756
      @jimwong7756 Месяц назад +1

      2^10=1024, it's a well known number.

  • @nikolayplatnov5148
    @nikolayplatnov5148 21 день назад +1

    Generally, Sn= 1+k+++k^n= (k^(n+1)-1)/(k-1), standard scholarship....

  • @TheNizzer
    @TheNizzer Месяц назад +9

    No idea why anyone competent in arithmetic would fail. Multiplying by 8.
    1, 8,64,512,4096,32768. Add them up.
    Absolutely no need for any factorising.

    • @youben3468
      @youben3468 Месяц назад

      Sum of geometric sequence terms,

    • @TheNizzer
      @TheNizzer Месяц назад

      @@youben3468yes, but you don’t even need that!

  • @Kwalliteht
    @Kwalliteht Месяц назад +6

    1+8+64+512+4096+32768=37449
    Can be done really fast without a calculator.

    • @onradioactivewaves
      @onradioactivewaves Месяц назад

      It can be done without calculation even, just write it in binary
      0b1001001001001

    • @andytraiger4079
      @andytraiger4079 Месяц назад +3

      As a digital electronics designer in the field of Digital Signal Processing for 25+ years, I approve of this method. The powers of two have been drilled into my head through endless repetition and I can instantly tell you any power of two up to 2^32.

  • @osj237
    @osj237 Месяц назад +3

    I would just put my 10 cents in by pointing out that you cna take advantage of the fact that 8 is 2 to the power of 3. Using this you can directly rewrite the answer in binary form as 11111000, This reduces the problem from an equation of powers to a simple mulitplication and addition problem.
    Bit 1::2 to the power of 0 is 1
    Bit 2 : 2 to the power of 1 is 2
    Bit 3: 2 to the power of 2 is 4
    Bit 4: 2 to the power of 3 is 8
    Bit 5: 2 to the power of 4 is 16
    Bit 6: 2 to the power of 5 is 32
    Bit 7: 2 to the power of 6 is 64
    Bit 8: 2 to the power of 7 is 128
    Bit 9: 2 5o the power of 8 is 256
    Bit 10:2 to the power o f 9 is 512
    Bit 11: 2 to the power of 10 is 1024
    Bit 12: 2 to the power of 11 is 2048
    Bit :13: 2 to the power of 12 is 4096
    Bit 14 :2 to the power of 13 is 8192
    Bit 15: 2 to the power of 14 is 16384
    Bit 16: 2 to the power of 15 is 32768
    Now: You just have to add the values for 2 to the power of 3*0, 2 to the power of 3*1, 2 to the power of 3*2, 2 to the power of 3*3, 2 to the power of 3*4, and
    2 to the power of 3*5., or you can express it in binary form as 0100 1001 0010 0100. (This is easily converted to hexadesumal notation as well.)

  • @WitchasanSirikhup
    @WitchasanSirikhup 26 дней назад +1

    64*65 = 32*2*13*5 = 32*13*10

  • @elijahlaukokchai
    @elijahlaukokchai Месяц назад +2

    11111(base8)=1/7(77777)=1/7(100000-1)
    =1/7*((8^6)-1)

  • @Xiaomizx_
    @Xiaomizx_ 13 дней назад +2

    Geometric progression formule : Am I a joke to you?

  • @vitalikwiskarik937
    @vitalikwiskarik937 23 дня назад +1

    64х65=65х65-65=4225-65=4160

  • @rainerzufall42
    @rainerzufall42 Месяц назад +3

    Most easy answer: 1001001001001001 (binary)

  • @muthusamyvee185
    @muthusamyvee185 Месяц назад +1

    64*65=65*65-65=4225-65=4160

  • @leolacic9442
    @leolacic9442 Месяц назад +1

    Derivacija točke x0 iznad osi x je 1, a derivacija kad je točka na osi x, 0>0 je 0. Na to sam mislio. Moglo bi biti točno, ali i ne mora biti. Ne sjećam se što sam učio, ali mislim da sam učio da je 0>0 =1, makar mi to nema logike.

  • @srinivasch-re2oq
    @srinivasch-re2oq Месяц назад +3

    If we know value of Log8 then we can solve very easily without any calculator with simple multiplications. Every person who attends such exams will prepare to know Log1 to Log20 values, so that most of the problems can be solved.

    • @TheNizzer
      @TheNizzer Месяц назад +1

      Anyone attending any such exam who fails to just x8 and uses logs is failing as they can’t use an appropriate solution. My 10 year old niece could do this problem a year ago.

  • @melhemhamade4210
    @melhemhamade4210 Месяц назад

    It is a sum of terms of geometric serie!!!!!

  • @nenedillats2999
    @nenedillats2999 Месяц назад

    = 8《 8 { 8 [ 8 ( 8 + 1 ) + 1 ] + 1 } + 1 》+ 1 and you have only add 1 and multiply by 8 (i.e multiply 3 times per 2) several times, in fact only simple calculations.

  • @nikokso
    @nikokso Месяц назад +1

    Wow really good job 🎉🎉🎉

  • @johntoe6127
    @johntoe6127 Месяц назад +1

    The solution proposed looks like something a Harvard Grad would produce. Meanwhile...I just multiplied it out. Took about 30 sec. even without a calculator.

  • @adgf1x
    @adgf1x Месяц назад

    8^3.73+73=73(512+1)=73×513.ans

  • @gregcheng2369
    @gregcheng2369 Месяц назад +1

    等比数列求和都能算是奥林匹克题了?

  • @vineetsharma6816
    @vineetsharma6816 Месяц назад +1

    Probably person is educated upto class 10th only and is unaware of geometric progression

  • @ying-yutzou7692
    @ying-yutzou7692 Месяц назад +1

    A stupid problem

  • @Rafnunes
    @Rafnunes Месяц назад

    8^6 - 1
    Or 2^18 -1

  • @walterwen2975
    @walterwen2975 Месяц назад

    Harvard Entrance Exams: 8⁵ + 8⁴ + 8³ + 8² + 8¹ + 8⁰ =?
    (8⁵ + 8⁴) + (8³ + 8²) + (8¹ + 8⁰) = 8⁴(8 + 1) + 8²(8 + 1) + (8 + 1) = (9)(8⁴ + 8²) + 9
    8⁴ + 8² = 8²(8² + 1) = (64)(65) = (60 + 4)(60 + 5) = 3600 + 9(60) + 20 = 4160
    8⁵ + 8⁴ + 8³ + 8² + 8¹ + 8⁰ = (9)(8⁴ + 8²) + 9 = (10 - 1)(4160) + 9 = 41600 - 4151 = 37449

  • @georgejo7905
    @georgejo7905 26 дней назад +1

    16 bits
    1001001001001001

  • @carlhopkinson
    @carlhopkinson 28 дней назад +1

    That is just 111111 base 8..

  • @LonnieHammock-k4n
    @LonnieHammock-k4n Месяц назад +1

    37449 no calculator

  • @alexandremaireno-ni4ec
    @alexandremaireno-ni4ec Месяц назад +1

    God! Why not 64.65 = 4160 ?

  • @sahdeolaldadsena915
    @sahdeolaldadsena915 Месяц назад +1

    बारबार विस्तार करना ठीक नही

  • @Patralgan
    @Patralgan Месяц назад +1

    Really? That seems really easy

  • @rabotaakk-nw9nm
    @rabotaakk-nw9nm Месяц назад

    8:03 (10-1)(4161)=
    =41610
    - 4161
    =37449 😁

  • @riyatmoko8241
    @riyatmoko8241 Месяц назад

    1438

  • @Ajaykumar123_rcm
    @Ajaykumar123_rcm Месяц назад +1

    37449

  • @евгенийшестернин-х9ц
    @евгенийшестернин-х9ц 15 дней назад +1

    39448

  • @vineetsharma6816
    @vineetsharma6816 Месяц назад

    Aise kaun karta hai

  • @王源輝-e8v
    @王源輝-e8v Месяц назад +2

    Show smart, it is(8^6-1)/7

    • @youben3468
      @youben3468 Месяц назад

      Exactly, sum geometric sequence terms,

  • @robertocarniato6195
    @robertocarniato6195 Месяц назад

    prolisso

  • @nucki222
    @nucki222 Месяц назад

    Käse

  • @nareshmehndiratta
    @nareshmehndiratta Месяц назад +1

    I m from India , you can ask me some problems and solutions , pay me ten dollars per hour

  • @shannonhgau7431
    @shannonhgau7431 17 дней назад +1

    Not smart

  • @playerjonas2747
    @playerjonas2747 10 дней назад +1

    37448