Math task for kids - dare to solve it? :)

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  • just a punk
    So fuckin' bored
    • Jun 2003
    • 32385

    #1

    Math task for kids - dare to solve it? :)

    My son (he is 13 BTW), just asked me to help him with this school math task:

    What is a sum of figures (digits) in the result of the simple expression below?
    2^2008 * 5^2011

    I've solved it with my son already, but will someone here able to solve it? Remember it's a just a homework task for 13 y.o. kids

    P.S. "^" in that expression is a power sign (to raise a given number to the given power)
    Obey the Cowgod
  • just a punk
    So fuckin' bored
    • Jun 2003
    • 32385

    #2
    Hmm.. 21 views and no single try to solve it? C'mon guys, it's just a standard school task for kids, but not something from a high math course!
    Obey the Cowgod

    Comment

    • just a punk
      So fuckin' bored
      • Jun 2003
      • 32385

      #3
      By sum of figures, I meant the following:
      124 = 1+2+3 = 6
      10082 = 1+0+0+8+2 = 11
      7 = 7 = 7
      82637 = 8+2+6+3+7 = 26
      etc..
      Obey the Cowgod

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      • quantum-x
        Confirmed User
        • Feb 2002
        • 6863

        #4
        Answer is 8
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        • ShaveBucks
          Confirmed User
          • Mar 2005
          • 467

          #5
          Originally posted by cyberxxx
          By sum of figures, I meant the following:
          124 = 1+2+3 = 6
          If I was your son, I'd never ask for your help again

          Comment

          • just a punk
            So fuckin' bored
            • Jun 2003
            • 32385

            #6
            Originally posted by ShaveBucks
            If I was your son, I'd never ask for your help again
            Just a typo of course
            Obey the Cowgod

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            • just a punk
              So fuckin' bored
              • Jun 2003
              • 32385

              #7
              Originally posted by quantum-x
              Answer is 8
              The answer is accepted. Anyone else?

              I will tell which one is right and will show the calculation if necessary, but just let's wait for more answers. Don't post your calculations please, just the answers. Otherwise it won't be interesting.
              Obey the Cowgod

              Comment

              • quantum-x
                Confirmed User
                • Feb 2002
                • 6863

                #8
                Originally posted by cyberxxx
                The answer is accepted. Anyone else?

                I will tell which one is right and will show the calculation if necessary, but just let's wait for more answers. Don't post your calculations please, just the answers. Otherwise it won't be interesting.
                zzzzz - the answer is 8.
                You can even do it in windows calculator if you're lazy.
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                • woj
                  <&(©¿©)&>
                  • Jul 2002
                  • 47880

                  #9
                  The answer is 12500....0000 so 8, come on, not very hard...
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                  • Eva PSC
                    Confirmed User
                    • Feb 2008
                    • 994

                    #10
                    Originally posted by woj
                    The answer is 12500....0000 so 8, come on, not very hard...
                    this is one crazy pic in your avatar, my eyes hurt to look at it while trying to figure it out lol

                    nice shop job

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                    Eva ICQ: 225 740 053

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                    • woj
                      <&(©¿©)&>
                      • Jul 2002
                      • 47880

                      #11
                      It looks tricky, but a quick flashback to grade 6 math, and you get:

                      2^2008 * 5^2011 = (2^2008)*(5^2008)*(5^3)=125*(10^2008)
                      Custom Software Development, email: woj#at#wojfun#.#com to discuss details or skype: wojl2000 or gchat: wojfun or telegram: wojl2000
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                      • L-Pink
                        working on my tan
                        • Mar 2005
                        • 39151

                        #12
                        Originally posted by ShaveBucks
                        If I was your son, I'd never ask for your help again

                        Comment

                        • D
                          Confirmed User
                          • Jan 2006
                          • 7412

                          #13
                          Why would we keep it going after the first answer was the right one?
                          -D.
                          ICQ: 202-96-31

                          Comment

                          • just a punk
                            So fuckin' bored
                            • Jun 2003
                            • 32385

                            #14
                            Originally posted by woj
                            It looks tricky, but a quick flashback to grade 6 math, and you get:

                            2^2008 * 5^2011 = (2^2008)*(5^2008)*(5^3)=125*(10^2008)
                            Congrats! This is the only right answer. Windows calculator is not an option, because you have to prove the solution. In a way as woj did above.
                            Obey the Cowgod

                            Comment

                            • quantum-x
                              Confirmed User
                              • Feb 2002
                              • 6863

                              #15
                              Originally posted by cyberxxx
                              Congrats! This is the only right answer. Windows calculator is not an option, because you have to prove the solution. In a way as woj did above.


                              As I said, you can *also* do it in calculator.
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                              • just a punk
                                So fuckin' bored
                                • Jun 2003
                                • 32385

                                #16
                                Originally posted by D
                                Why would we keep it going after the first answer was the right one?
                                Because after that, the one should be explaining on how he got it. As I said, Windows calc is not a right way to do that (you won't have it on a school's exam)
                                Obey the Cowgod

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                                • tranza
                                  ICQ: 197-556-237
                                  • Jun 2003
                                  • 57559

                                  #17
                                  Boring.......
                                  I'm just a newbie.

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                                  • ADL Colin
                                    Too lazy to set a custom title
                                    • Feb 2001
                                    • 11929

                                    #18
                                    Originally posted by D
                                    Why would we keep it going after the first answer was the right one?
                                    to look for wrong ones


                                    Adult Date Link - $50 PPS starting NOW! -- good and JUICY!

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                                    • just a punk
                                      So fuckin' bored
                                      • Jun 2003
                                      • 32385

                                      #19
                                      Originally posted by quantum-x


                                      As I said, you can *also* do it in calculator.
                                      Sorry, I've missed that *also*. Course if you did it manually, your answer is also correct.
                                      Obey the Cowgod

                                      Comment

                                      • just a punk
                                        So fuckin' bored
                                        • Jun 2003
                                        • 32385

                                        #20
                                        Originally posted by woj
                                        The answer is 12500....0000 so 8, come on, not very hard...
                                        Ok, here is another one from a same today's homework.

                                        1*2*3*...*n = 2^15*3^6*5^3*7^2*11*13

                                        What is n there?
                                        Obey the Cowgod

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                                        • Tubestone
                                          Confirmed User
                                          • Feb 2008
                                          • 189

                                          #21
                                          1+1+1+1+1+1+1+1= 8

                                          Comment

                                          • munki
                                            Do Fun Shit.
                                            • Dec 2004
                                            • 13393

                                            #22
                                            The answer is 42

                                            I have the simplest tastes. I am always satisfied with the best.” -Oscar Wilde

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                                            • woj
                                              <&(©¿©)&>
                                              • Jul 2002
                                              • 47880

                                              #23
                                              Originally posted by cyberxxx
                                              Ok, here is another one from a same today's homework.

                                              1*2*3*...*n = 2^15*3^6*5^3*7^2*11*13

                                              What is n there?
                                              16 ....
                                              Custom Software Development, email: woj#at#wojfun#.#com to discuss details or skype: wojl2000 or gchat: wojfun or telegram: wojl2000
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                                              • just a punk
                                                So fuckin' bored
                                                • Jun 2003
                                                • 32385

                                                #24
                                                Originally posted by munki
                                                The answer is 42
                                                Course it's a wrong answer BTW, it's ok to post your calculations to show it wasn't solved with a windows calc
                                                Obey the Cowgod

                                                Comment

                                                • D
                                                  Confirmed User
                                                  • Jan 2006
                                                  • 7412

                                                  #25
                                                  Originally posted by cyberxxx
                                                  Ok, here is another one from a same today's homework.

                                                  1*2*3*...*n = 2^15*3^6*5^3*7^2*11*13

                                                  What is n there?
                                                  n = 16
                                                  -D.
                                                  ICQ: 202-96-31

                                                  Comment

                                                  • D Ghost
                                                    null
                                                    • May 2006
                                                    • 9819

                                                    #26
                                                    math is for calculators

                                                    Comment

                                                    • munki
                                                      Do Fun Shit.
                                                      • Dec 2004
                                                      • 13393

                                                      #27
                                                      Originally posted by cyberxxx
                                                      Course it's a wrong answer BTW, it's ok to post your calculations to show it wasn't solved with a windows calc
                                                      No it's not...

                                                      The answer is always 42...


                                                      I have the simplest tastes. I am always satisfied with the best.” -Oscar Wilde

                                                      Comment

                                                      • aico
                                                        Moo Moo Cow
                                                        • Mar 2004
                                                        • 14748

                                                        #28
                                                        Originally posted by ShaveBucks
                                                        If I was your son, I'd never ask for your help again

                                                        Comment

                                                        • just a punk
                                                          So fuckin' bored
                                                          • Jun 2003
                                                          • 32385

                                                          #29
                                                          Still no one is able to prove the answer with formula?
                                                          Obey the Cowgod

                                                          Comment

                                                          • quantum-x
                                                            Confirmed User
                                                            • Feb 2002
                                                            • 6863

                                                            #30
                                                            Originally posted by cyberxxx
                                                            Still no one is able to prove the answer with formula?
                                                            We're bored of this already.
                                                            PrettyInCash.com - BoozedGFs.com - TeenGFs.com - JizzGFs.com- MilfUploads.com -

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                                                            • D
                                                              Confirmed User
                                                              • Jan 2006
                                                              • 7412

                                                              #31
                                                              Originally posted by cyberxxx
                                                              Still no one is able to prove the answer with formula?
                                                              We wrote the answer, already. :-P

                                                              It's just a matter of expanding the right of the equality and then rewriting it in factorial form.

                                                              2^15*3^6*5^3*7^2*11*13=

                                                              2x2x2x2x2x2x2x2x2x2x2x2x2x2x2x3x3x3x3x3x3x5x5x5x7x 7x11x13=

                                                              2x3x(2x2)x5x(2x3)x7x(2x2x2)x(3x3)x(2x5)x11x(2x2x3) x13x(2x7)x(3x5)x(2x2x2x2)=

                                                              2x3x4x5x6x7x8x9x10x11x12x13x14x15x16=

                                                              16 factorial=

                                                              16x15x14x13x12x11x10x9x8x7x6x5x4x3x2x1=

                                                              1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16

                                                              n=16

                                                              Q.E.D.

                                                              Still... good to see a father taking such an interest in his son's math homework. If more did so, I think we'd be further along a better path.
                                                              Last edited by D; 03-20-2008, 01:17 PM.
                                                              -D.
                                                              ICQ: 202-96-31

                                                              Comment

                                                              • just a punk
                                                                So fuckin' bored
                                                                • Jun 2003
                                                                • 32385

                                                                #32
                                                                Originally posted by D
                                                                Q.E.D.
                                                                Very impressive! I know nothing about your math background but it's much above the average webmaster here, because I mentioned the number of topic views but only D gave a right answer to the second task.

                                                                Originally posted by D
                                                                Still... good to see a father taking such an interest in his son's math homework. If more did so, I think we'd be further along a better path.
                                                                Thanks, I'm just to see him growing smart. I believe I do like every other parent.
                                                                Obey the Cowgod

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