This program keeps accepting numbers from the user till he submits the number 0, then it prints out the sum of the numbers, the max, the min and the average and ends.

until_zero.rb

min = 0
max = 0
sum = 0
count = 0
input = ""
def results(min,max,avg)
	puts "End of program"
	puts "-------------------------"
	puts "The lowest number was: #{min}"
	puts "The highest number was: #{max}"
	puts "The average number was: #{avg}"
	puts "-------------------------"
end

puts "What's your name please?"
name = gets.chomp
puts "Hello " + name + "!"
while input != 0
	puts "Please type in a number!:\n"
	input = gets.chomp.to_f

	sum += input
	count += 1
	if input < min
		min = input
	elsif input > max
		max = input
	end
end

if count == 0
	results("0","0","0")
else
	results(min.to_s, max.to_s, (sum/count).to_s)
end