Question 1022510
<pre><font face = "consolas" color = "indigo" size = 4><b>
Good Morning!  
See Below ***
Note:
*[tex \LARGE \ \ \ \ \  \ \ \ b^y = x \ \ \ \ \ \Rightarrow\ \ \ \ \ \ \ y = \log_b(x) ]
2^d = 645
*[tex \LARGE \ \ \ \ \  \ \ \ 2^d = 645 \ \ \ \ \ \Rightarrow\ \ \ \ \ \ \ d = \log_2 (645) ]
base conversion formula 
{{{log(a, p) = log(b,p)/ (log(b, a)) }}}
d = {{{log(2,645) = log(10,645)/ (log(10, 2)) }}} = 2.8/.30 = 9.333...
{{{log(10,645)/ (log(10, 2)) }}}  Per Your Question***:  These are (base 10) 
Found by Your calculator by simply using log function(calculator automatically uses base 10) 
and entering either 645 0r 2
Checking:
2^9.33333 = 645 (rounded)  Checks!