I am not sure how many of you might find this useful..but for Asian students familiar with log function...it might help

A. 999^12= 10^36=> 36 log 10 =>36

D. 20^24= As 20 is less than 3^3..thus 20^24 < 27^24 => 3^42 => 42 log 3 => 42 x 0.47 = Approx. 20

E. 15^20 < 2 ^80 => 80 log 2 = 80 x 0.3 = 24

Log values have a direct correlation with numerical value of the number...

I had learnt the values of log 3= .4771 and log 2= 0.3010 in my school days... surprisingly I was able to accurately retrieve these from my memory slot

Additionally log 1 = 0, log 10 = 1, log 100 = 2...(I guess)

I would be glad if Bunuel or Karishma validate my approach...Just to make things more clear

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Appreciate the efforts...KUDOS for all

Don't let an extra chromosome get you down..