Why Python is fail to calculate basic math problems?

When i was trying this:

a = input("Enter your math calculations :")

if "45*3" or "45 * 3" in a:
    print("555")
elif "56+9" or "56 + 9" in a:
    print("77")
elif "56/6" or "56 / 6" in a:
    print("4")
else:
    print(eval(a))

Instead of expected answer it is outputting unexpected output

Expected : Enter your math calculations :10+1 =
11

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Result : Enter your math calculations :10+1 =
555

What am i doing wrong???.

>Solution :

Why did you write if "45*3" or "45 * 3" in a:

Instead write if a=="45*3" or a=="45 * 3":

and all like this.