If log_10{ log_10[ log_10( log_10 N ) ] } = 0, find N.

Difficulty: Medium

Correct Answer: 10^(10^10)

Explanation:


Introduction / Context:
Nesting logarithms requires peeling them one by one from the outside in. The key fact is log_10(A) = 0 implies A = 1. Applying this repeatedly determines the inner values stepwise until N is obtained.


Given Data / Assumptions:

  • log_10{ log_10[ log_10( log_10 N ) ] } = 0.
  • All log arguments must be positive.


Concept / Approach:
Let the innermost value be t_1 = log_10 N. Then set t_2 = log_10(t_1), t_3 = log_10(t_2). The given states log_10(t_3) = 0 ⇒ t_3 = 1. Work backward to find N.


Step-by-Step Solution:

log_10(t_3) = 0 ⇒ t_3 = 1But t_3 = log_10(t_2) ⇒ log_10(t_2) = 1 ⇒ t_2 = 10t_2 = log_10(t_1) ⇒ log_10(t_1) = 10 ⇒ t_1 = 10^{10}t_1 = log_10 N ⇒ log_10 N = 10^{10} ⇒ N = 10^{(10^{10})}


Verification / Alternative check:
Substitute forward: log_10 N = 10^{10}; log_10(10^{10}) = 10; log_10(10) = 1; log_10(1) = 0 ✓.


Why Other Options Are Wrong:
10^10 and 10^100 are intermediate inner values (t_1 or a confusion), not N; 10^1010 misreads exponent placement.


Common Pitfalls:
Losing track of nesting levels or assuming log_10(0)=… (undefined). Maintain positivity of each inner argument.


Final Answer:
10^(10^10)

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