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2018-10-08 Basic


3333= ? \Huge \color{#69047E}\sqrt[3]{\color{#20A900}3^{\color{#3D99F6}{3}^{\color{#D61F06}{3}}}} \color{#EC7300}=\ ?


  • 333=3(33)\displaystyle \large 3^{3^3} = 3^{ \left(3^3 \right) }
  • 333(33)3\displaystyle \large 3^{3^3} \ne { \left(3^3 \right) }^3

x=11111...11111Number of 1s = 10022222...22222Number of 2s = 50\large x = \underbrace{11111...11111}_{\text{Number of 1s = 100}} - \underbrace{22222...22222}_{\text{Number of 2s = 50}}

What is the sum of digits in x?x?

Hint: Try it with smaller numbers first. For example, find the sum of digits in 111111222.111111 - 222.

I know that just adding numerators and denominators doesn’t work. For example,

12+231+22+3.\frac{1}{2}+\frac{2}{3} \ne \frac{1+2}{2+3}.

Curious if this kind of addition ever works, I look for positive integers a,b,c,da,b,c,d such that

ab+cd=a+cb+d. \dfrac ab + \dfrac cd = \dfrac{a+c}{b+d}.

After some searching, I conclude that such numbers don't exist. Am I right?

A system of two symmetrical, identical, water-filled jars is fixed on a turntable. Each jar has a cork—attached to the bottom by a thread—floating vertically.

What will happen to the corks when the turntable starts rotating?

Details and Assumptions:

  • The jars are closed so that no water spills out.

What is the length of BC?BC?


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