A couple of different ways to test whether a number is a number, even if you receive it as a string.

test a number in Ruby

def isInt?(number)
  true if Integer(number) rescue false
end

isInt?("13")

result = true if Integer("12") rescue false # true
result = true if Integer("test") rescue false #false
result = true if Float("test") rescue false #false
result = true if Float(13.2) rescue false #true