Question 20664
you mean log 5 to base 10=0.6990 etc..since all logs are to base 10 we may take it for granted and drop writing that base..so we have 
log 5 = 0.6990
log 7 =0.8451
to find log 0.05
log 0.05=log (5/100)=log 5 - log 100 = 0.6990 - 2 = -1.3010...
since log 100 to base 10 =2...note that 10^2 = 100 ....
hence by definition  log 100 to base 10 =2..