Beginner question: help ensuring input is a number

[ezdev]

ck = ""
while type(ck) == str:
    odds_text = ("The number is ")
    odds_input = input("Enter a number: ")
    strip_input = odds_input.strip()
    try:
        ck = float(strip_input)
    except:
        print("Sorry, please enter a valid number") ; ck = ""