i have found that the mantissa(M)for a number X can be approximated by a simple formula
M= y(19-y)
where y= X written such that 3>y<8eg. find log of 558?
here y=5.58, M= 5.58*(19-5.58)=74.8866
THUS log 558 = 2.748866 (approximately) the correct answer is 2.7466
if y is not lying within 3 to 8 then modify X to obtain y within the range
eg. find log of 11?
here 11 can be written as 33/3
log(11)= log(33/3)=log33-log3
for 33,Y=3.3 M=3.3*(19-3.3)=51.81, log33=1.5181
for 3, y=3, M=48, log3 =0.48
log11 =log33 -log3 =1.5181-0.48=1.03.
is there a better formula, and even if any for finding the antilog
ranjitr
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