Ladder Of Magnitude

Algebra Level 3

10 ÷ ( 1 0 2 ÷ ( 1 0 3 ÷ ( ÷ ( 1 0 99 ÷ 1 0 100 ) ) ) = ? \large 10 \div (10^2 \div (10^3 \div ( \cdots \div (10^{99} \div 10^{100})\cdots))= \, ?

1 1 0 100 10^{-100} 10 1 0 50 10^{-50} 1 0 100 10^{100}

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Eli Ross Staff
Jan 21, 2016

This is a problem where I like to find a pattern before formalizing.

Note that 1 0 99 ÷ 1 0 100 = 1 0 1 . 10^{99} \div 10^{100} = 10^{-1}.

Then, 1 0 98 ÷ 1 0 1 = 1 0 99 . 10^{98} \div 10^{-1} = 10^{99}.

Then, 1 0 97 ÷ 1 0 99 = 1 0 2 . 10^{97} \div 10^{99} = 10^{-2}.

Then, 1 0 96 ÷ 1 0 2 = 1 0 98 , 10^{96} \div 10^{-2} = 10^{98}, and so on.

Continuing this pattern, we will get 1 0 50 10^{-50} for the entire result.

To formalize the solution, we can set a 1 = 1 0 99 ÷ 1 0 100 = 1 0 1 a_1 = 10^{99} \div 10^{100} = 10^{-1} and a k = 1 0 100 k ÷ a k 1 a_k = 10^{100-k} \div a_{k-1} for k = 2 , 3 , , 99. k=2,3,\ldots,99. Using induction , we can prove the pattern we saw above.

That's a really great solution!

Fin Moorhouse - 5 years, 4 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...