class(1.5)
# "numeric"
class(1)
# "numeric"
class(1L)
# "integer"
x <- as.numeric("3")
x
# 3
class(x)
# "numeric"

def key_in_a_number():
    num = input("Key in a number here: ")
    try:
        return float(num)
    except ValueError:
        return "Please key in only numbers."

def key_in_a_number():
    num = input("Key in a number here: ")
    try:
        return int(num)
    except ValueError:
        try:
            return float(num)
        except ValueError:
            return "Please key in only numbers."