Mine
public text v1 · immutablelist = []
def palindrome? n
a = n.to_s.split('').map {|x| x.to_i}
b = 0
i = 0
a.each do |m|
b += m*10**i
i += 1
end
b == n ? n : nil
end
(100..999).each do |n|
m = n
while m > 99
list << m * n
m -= 1
end
end
puts list.sort.map{|x| palindrome? x}.compact.uniq.sort[-1]