Change the base of Log

Log with base 2 i.e Log2 :
Log2(2) = 1
Log2(8) = 3

Log with base 10 i.e Log10 :
Log10(10) = 1
Log10(1000) = 3

Formula to find Log of base 2 using Log of base 10:
Log2(X)=Log10(X)/Log10(2)

Find Log2(8) using calculator? (Wait my calculator doesn't know how to find Log with base 2)
No problem, use the base conversion formula
Example:
Log2(8)=Log10(8)/Log10(2)


Other Log formulae:
log_b(xy) = log_bx + log_bylog_b(x/y) = log_bx − log_by
log_b(x^y) = y log_bx


References:
http://oakroadsystems.com/math/loglaws.htm