Question 166
The national debt of the United States is on track to reach $5 \times 10^{13}$ dollars by 2033. How many digits does this number of dollars have when written as a numeral in base 5? (The approximation of $\log_{10} 5$ as 0.7 is sufficient for this problem.)
(A) 18 (B) 20 (C) 22 (D) 24 (E) 26
(A) 18 (B) 20 (C) 22 (D) 24 (E) 26