How to convert a string variable to int?

As mentioned in the other answers, the return of the input() function is type string , the same is true for raw_input() function in Python 2.x .

numero1 = int(input("Informe um numero: "))
numero2 = int(input("Informe um numero: "))

Also consider handling possible exceptions that might occur, for example exception ValueError that is thrown when a function receives an argument that has the right type but an invalid value.

See:

try:
    numero1 = int(input("Informe um numero: "))
    numero2 = int(input("Informe um numero: "))

    soma = numero1 + numero2
    print ("{0} + {1} = {2}".format(numero1, numero2, soma))

except ValueError:
    print("Somente numeros sao aceitos. Tente novamente.")

View demonstração

You have to convert the string , which is the return of the function input , to a number:

n1 = input ("informe um número ")
n2 = input ("informe um número ")
soma = int(n1) + int(n2)
print ("O resultado da soma de", soma)

See running on ideone .

Function documentation .

The input recognizes the values in the form of a string. then you should do the following:

soma = int(n1) + int(n2)

int (), makes the values numbers