Question: Suppose I have a list:

```
lst = [0, 1, 0, 0]

```

How can I make python interpret this list as a binary number 0100 so that `2*(0100)` gives me `01000`?

The only way that I can think of is to first make a function that converts the "binary" elements to corresponding integers(to base 10) and then use bin() function..

Is there a better way?

Answer: 
This is not a fancy one-liner, but simple and fast.

```
lst = [0,1,1,0]

num = 0
for b in lst:
    num = 2 * num + b
print(num) # 6

```
In Jupyter:-
------------

```
lst = [4,5,7,1,2]
bin(int(''.join(map(str, lst)))<<1)

```

o/p:- '0b10110010100100000'

In Python Shell:-
-----------------

```
>>> lst =[4,5,7,1,2]
>>> bin(int(''.join(map(str, lst)))<<1)

```

o/p:- '0b10110010100100000'