Problem:
If log2(log2(log2(x)))=2, then how many digits are in the base-ten representation for x?
Answer Choices:
A. 5
B. 7
C. 9
D. 11
E. 13
Solution:
Since
log2(log2(log2(x)))=2⟺log2(log2(x))=22=4,⟺log2(x)=24=16⟺x=216=26⋅210≈64⋅1000,
it follows that x has 5 base-ten digits.