Use the form below to do your conversion.
Solution
Step1
Log21391=Log(391) ÷ Log(21)
Log(391)= 2.5921767573959
Log(21)=1.3222192947339
Log21391=2.5921767573959 ÷ 1.3222192947339
Ans=1.9604741571386
Step2
Alternatively, the logarithm can be calculated like this.