1- how can I find out log and anti log approximate value on the basis of mean values ex if I know log 4 and log 6 value than I can easygoing find value for log 5 it will be intermediate of both . Means for time saving immidiate approach answer for anti log how can we?.
Firstly, there's some confusion sir, the question you referred is no way related to log.
To find unknown logs from the known ones you first need to know the following properties.
The general way is to learn the log of prime numbers (2,3,5,7 etc) and then apply the above mentioned properties to find log of required number.
For ex.
If you know log2 and log3 you can easily find log6 by following method:
log6 = log(2*3) = log2 + log3
similarly,
log4 = log (2^2) = 2 log2
Hope this helps !!!