A culture of bacteria starts with $50$ bacteria and increases exponentially.
The relationship between $B$, the number of bacteria in the culture, and $d$, the elapsed time, in days, is modeled by the following equation.
$B=50\cdot 10\^{\Large{\frac{d}2}}$
**In how many days will the number of bacteria in the culture reach $800{,}000$?**
*Give an exact answer expressed as a base-ten logarithm.*
[[☃ expression 1]] days