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If 2-1=3 what is 10-10=???

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by 15 Comments

Number Puzzle #161
if-2-1-3
If
2-1=3
4-4=0
8-5=40
10-10=???
Check your answer:-

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here a-b=axa+(a/2)x(a/2)-axb

2-1=2×2+(2/2)x(2/2)-2×1=3
8-5=8×8+(8/2)x(8/2)-8×5=40
4-4=4×4+(4/2)x(4/2)-4×4=4
thus
10-10=10×10+(10/2)x(10/2)-10×10=25

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  1. Harvey Lerman says

    a-b=???
    axa+(a/2)x(a/2)-axb=answer
    10-10=10×10+(10/2)x(10/2)-10×10=25

    2-1=2×2+(2/2)x(2/2)-2×1=3
    8-5=8×8+(8/2)x(8/2)-8×5=40
    4-4=4×4+(4/2)x(4/2)-4×4=4

    Reply

  2. Harvey Lerman says

    Answer to puzzle:
    10-10=25
    Format of puzzle:
    a-b=?
    Equation:
    a*+(a/2)*-axb [where * means square, x=mult]
    Could be stated as (5a*/4-axb)

    So 10-10:
    10×10+[10/2]x[10/2]-10×10=
    100+5×5-100=25

    extra
    8-5:
    8×8+4×4-8×5=64+16-40=40

    Reply

    • Sat Battoo says

      Sorry Harvey, I’m not getting it.
      1) How did you come up with the equation?
      2) When you say a* + (a/2)* – axb, could be stated as (5a* / 4-axb), these two are not equal.
      3) a* + (a/2)* – axb works for the first part, 2-1=3 and also 8-5=40 but doesn’t work for 4-4=0 because 4-4 works out to be -4.
      4) The (5a* / 4-axb) formula doesn’t work for any of them.
      Please advise.

      Reply

      • Harvey Lerman says

        It’s confusing because I can’t type subscripts, etc.

        1. (half of a)-squared can be written as (a/2)-squared or a-squared/2-squared which is a-squared/4.

        2. also a-squared can be written as (4 a-squared)/4

        adding these together gives (5a-squared)/4

        So they are the same and either way you put it all together gives the correct answers to all the examples I gave, including the equation:
        10-10=25.

        4-4=(16+4)-16=4

        10-10=(100+25)-100=25

        Reply

        • Harvey Lerman says

          Hope the “a-squared” doesn’t get confused with “-” used as “minus”.
          I should have used maybe “a_squared”

          Reply

  4. Harvey Lerman says

    Let me know when you all give up and I’ll tell you the correct answer. Or I can give you other examples: 6-3=27 also 4-2=12

    Reply

    • Deepti Singhal says

      Hi the logic is
      2-1=3 ( actually its addition)
      4-4=0 (actually its subtraction)
      8-5=40 (actually it multiplication)
      since all the arithmetic operations are used only pending is division

      hence 10-10=1 (actually it is 10/10=1)

      i hope you got it!!

      Happy Puzzling 😀

      Reply

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