在Python中，当你把两个字符串加在一起时，你就把它们的值连接起来了。
下面是一个更简单的示例：

string_one = "hello"
string_two = " "
string_three = "there"
final = string_one + string_two + string_3

print(final) # hello there

要用数学方法将它们相加，需要确保值是整型、浮点型、小数型...

one = 1
two = 2
final = one + two

print(final, type(final)) # 3 int

因此，对于您的代码：

first_num = int(input('Please enter a number')) 
second_num = int(input('Please enter another number'))
final = first_num + second_num

print(final) # will give you the numbers added

但是，您是根据用户输入强制转换为int的，所以我保证您也会捕获当用户输入一个不能强制转换为int的值时发生的错误，比如hi。例如：

try:
    first_num = int(input('Please enter a number')) 
    second_num = int(input('Please enter another number'))

    print(first_num + second_num) # will give you the numbers added, if ints
except ValueError as ex:
   # if any input val is not an int, this will hit
   print("Error, not an int", ex)

试试这个

first_num = int(input('Please enter a number '))
second_num = int(input('Please enter another number '))
sum=first_num+second_num
print (sum)