How to do logarithms in coding?

Question

Hey coding brothers, now I'm creating a calculator in Ruby, but I don't know how to do logarithms...
Please, help me!

Answer 1

http://devdocs.io/ruby~2.4/math
http://devdocs.io/ruby~2.4/math#method-c-log

Answer 2

a=Math::log(100);
puts a
#2