2024 AMC 12B Problems/Problem 6: Difference between revisions
| Line 13: | Line 13: | ||
<cmath>\approx 19.5</cmath> | <cmath>\approx 19.5</cmath> | ||
Hence, our answer is <math>\textbf{(B) } 20</math> | Hence, our answer is <math>\fbox{\textbf{(B) } 20}</math> | ||
~tsun26 | ~tsun26 | ||
Revision as of 01:20, 14 November 2024
Problem 6
The national debt of the United States is on track to reach 
dollars by 
. How many digits does this number of dollars have when written as a numeral in base 5? (The approximation of 
as 
is sufficient for this problem)
Solution
The number of digits is just 
.
Note that
![\[\log_{5} 5\times 10^{13}=1+\frac{13}{\log_{10} 5}\]](http://latex.artofproblemsolving.com/d/1/e/d1e4245753973d10ebc097221da7f3bcb66a510a.png)
![\[\approx 1+\frac{13}{0.7}\]](http://latex.artofproblemsolving.com/c/b/6/cb6c371178c546b7b071a74c8a98d5852f2f520b.png)
![\[\approx 19.5\]](http://latex.artofproblemsolving.com/1/7/b/17bce86bb35886da1b4460f7e79c804aeefddec5.png)
Hence, our answer is 
~tsun26
