A culture of bacteria starts with 505050 bacteria and increases exponentially. The relationship between BBB, the number of bacteria in the culture, and ddd, the elapsed time, in days, is modeled by the following equation.
B=50⋅10d2
In how many days will the number of bacteria in the culture reach 800{,}000800,000800, comma, 000?
Give an exact answer expressed as a base-ten logarithm.