使用to_s(2)在ruby中将变量转换为二进制时接收错误

puts "Tell me a number:"
num1 = gets
puts "The number you gave in binary is " + num1.to_s(2)

但是我得到了“错误的参数数量(1到0)”错误.

有关如何进行的任何建议？

puts "The number you gave in binary is " + num1.to_i.to_s(2)