# Aptitude - Logarithm - Discussion

### Discussion :: Logarithm - General Questions (Q.No.2)

2.

If log 2 = 0.3010 and log 3 = 0.4771, the value of log5 512 is:

 [A]. 2.87 [B]. 2.967 [C]. 3.876 [D]. 3.912

Answer: Option C

Explanation:

log5 512
 = log 512 log 5
 = log 29 log (10/2)
 = 9 log 2 log 10 - log 2
 = (9 x 0.3010) 1 - 0.3010
 = 2.709 0.699
 = 2709 699
= 3.876

 Happy said: (Apr 23, 2011) How is log 10=1.

 Sumit said: (May 27, 2011) How can you get log (10/2) ?

 Kasthuri said: (Aug 6, 2011) If log 2 = 0.3010 and log 3 = 0.4771,and log 7 = 0.8451 then the value of log75 is?

 Jithu said: (Aug 19, 2011) @kasthuri. Can you explain the solution ?

 Sandy said: (Aug 20, 2011) log 10 means log 10 to the base 10 that ts equal to 1 so, log10=1

 Heaven.Bangladesh said: (Sep 1, 2011) @sumit Log 5=log(10/2).coz,10/2=5

 Shalini said: (Sep 3, 2011) @Kasthuri log 75= log(5*5*3) = log(5*5)+log(3), because log m*n=log m+log n =2 log5 +log3 =2 log(10/2)+log3 =2(log10-log2)+log3 =2(1-.3010)+..4771 =2*.699+.4771 =1.398+.4771 =1.8751

 Sinkay said: (Dec 6, 2011) If log 2=0.3010 and log 7=0.8451,

 Usha said: (Feb 22, 2013) If log2=0.3010 and log3= 0.4771, then log75 = ?

 Jeromy said: (Mar 15, 2013) Why are they dividing log 512 by log 5?

 Vigneshraj said: (Mar 25, 2013) @jeromy. Click the impotant formulas link there you can see 7th formula using that formula we divide log512 by log5.

 Lekan said: (Nov 1, 2013) Please who can solve this log10 2 = 0.3010?

 K.Rajeshreddy said: (Jun 1, 2014) log5512 = log512/log5 = 9log2/log5. = 9log2/log3+log2. = 9*0.3010/0.4771+0.3010. I think this is this the correct procedure as log 2 and log3 values are given. Why we need to go for log 10/2?

 Apoorva said: (Jul 6, 2014) Why is it only 2?

 Nirav said: (Jul 18, 2014) Why are they dividing log 512 by log 5? Is this a formula?

 Nagdish Kewat said: (Aug 19, 2014) What is the answer of log3(log2(log3t)) =1 t=?

 Raj Kumar said: (Aug 27, 2014) @Nirav. log512/log5 = 9log2/log(2+3) = 9log2/(log2*log3). = 9*.3010/(.3010*.4771). = 9/.4771 >18.

 Saurabh said: (Aug 30, 2014) Why are they dividing log 512 by log 5?

 Vipin Mishra said: (Sep 5, 2014) Formula: log a x = log x/log a. log 5 512 = log 512/log 5.

 Goose said: (Sep 19, 2014) log(75) = log(70+5). = log(7*10)+(2+3). = [log(7)+log(10)]*log(2)*log(3). = [0.8541+1]*0.3010*0.4771. = 1.8451*0.3010*0.4771. = 0.1557.

 Dhivi said: (Feb 14, 2015) Can you say the answer for the (5/512) power 1/9?

 Vaishu said: (Jun 10, 2015) If log 2 10 = 0.3010 and log 7 10 = 0.8451, then the value of log 2.8?

 Sumeet said: (Jun 28, 2015) {log(10/2) = log5} Can we write like this? I have a doubt!

 Sumeet said: (Jun 28, 2015) If log(10/2) = log5, then log(512/5) should be equal to log(9/1). Isn't it?

 Kate said: (Aug 14, 2015) Please I don't know anything about math I need help forms you guys.

 Ajitha said: (Nov 3, 2015) Can you explain it once for me?

 Ajitha said: (Nov 3, 2015) log5 512 = log 512/log5 by which formula.

 Ankur said: (Nov 23, 2015) Answer is right, but too long, tell in short.

 Girish said: (Dec 9, 2015) That is base change rule it seems log (b) to the base a, = log (b) to base c/log (a) to base c i.e log 512/log5.

 Pavan S@I said: (Mar 29, 2016) How to write log 4 power 2013, if log 2 = 0.3010? Please help me.

 Rita said: (Apr 3, 2016) Find the value of log2 + log3?

 Aman Srivastava said: (Apr 16, 2016) Which property of log is used in:- log5 512 = log 512/log 5.

 Grace Lancelot said: (Jun 21, 2016) From where did log10 - log2 came from?

 Koala said: (Jul 4, 2016) It is a basic formula of logarithm. If, log(a/b) = log a - log b log (a.b) = log a + log b

 Akash said: (Jul 17, 2016) If log (a + b)/7 = loga + logb/2 then show that a/b + b/a = 47. Can anyone solve this problem?

 Shyam said: (Aug 9, 2016) It's quite confusing.

 Rakesh.H said: (Aug 17, 2016) Simple way; In 512/ln 5 = 3.876.

 Naveen said: (Aug 28, 2016) If log 3 = .4771 than log 27 = ?

 Sarah said: (Sep 3, 2016) How did you know log 512 = 2^9?

 Kennedy said: (Sep 17, 2016) Please explain the last part are you supposed to divide or subtract?

 Sukh Singh said: (Oct 4, 2016) How to use Log3? Please explain me.

 Arban said: (Oct 22, 2016) How can log 10 be 1? It can only be 1 if the base is 10. If I remember the formula correctly then the base can be anything and is generally a random constant term (a, b etc. ). If we follow the same logic then the answer is most definitely wrong as per my calculations. CAN ANYONE EXPLAIN THE CORRECT PROCESS?

 Michael Essandoh said: (Nov 3, 2016) Please solve this, given that log 9 = 0.9542 and log 6 = 0.7781, find the value of log base 10 of 225.

 Saffee2 said: (Nov 30, 2016) @Michael Essandoh. Is it 2.5104?

 Anu said: (Jan 4, 2017) How to subtract 1 - 0.3010 =? Explain.

 Shreyash said: (Jan 5, 2017) @Arban. Whenever base is not mentioned, it is taken as 10. So, log 10 =1 (as the base here is 10).

 Mansi said: (Feb 21, 2017) Here Log2 =0.3010. Then, Find log 5.

 Mushariq said: (Mar 2, 2017) Nice explanation, thank you for all your solution.

 Ayesha said: (Jun 22, 2017) If log2=0.3010 then find the value of log32. Can someone solve this?

 Siddharth said: (Jun 29, 2017) @Ayesha. log32 = log(2^5)= 5log2=5*0.3010= 1.505.

 Manasa said: (Jul 21, 2017) Superb explanation, Thank you all.

 Dheeraj said: (Jul 22, 2017) @Naveen. log27=log3^3=3log3=3 * 0.4771=1.4313.

 Ankush Premi said: (Aug 1, 2017) How to solve this question 1-log5= 1/3 ( log1/2+logx +1/3 log5)? Can anyone solve this

 Bittu said: (Oct 5, 2017) Why do we take log base 10 in log table?

 Angel said: (Dec 18, 2017) Given that log 2 =0.3010 and log 3=0.4771 what is log 1.125?

 Dinesh Puri said: (Dec 29, 2017) When log3=0.4771 and log 5=0.690then find value of log 4=? Please solve this.

 Sweta said: (May 28, 2018) @Dinesh Puri. log 4=log 2^2. =2log2, =2log(10/5), = 2*{log10-log5}, = 2*{1-.690}, = 0.62.

 Aman Mittal said: (Jun 6, 2018) Log base is 5 and exponential is 512 so how you kept log5=log512?

 Simran said: (Sep 4, 2018) Can anyone explain it properly?

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