Ruby 2.4 adds infinite? and finite? methods to Numeric Prior to Ruby 2.4 Prior to Ruby 2.4, Float and BigDecimal responded to methods infinite? and finite?, whereas Fixnum and Bignum did not. Ruby 2.3 #infinite? 5.0.infinite? => nil Float::INFINITY.infinite? => 1 5.infinite? NoMethodError: undefined method `infinite?' for 5:Fixnum #finite? 5.0.finite? => true 5.finite? NoMethodError: undefined met