How to strip off left side of binary number in Python?


I got this binary number 101111111111000

I need to strip off the 8 most significant bits and have 11111000 at the end.

I tried to make 101111111111000 << 8, but this results in 10111111111100000000000, it hasn’t the same effect as >> which strips the lower bits. So how can this be done? The final result MUST BE binary type.


You can get the rightmost 8 bits of an integer n using bitwise-and:


255 is the sum of the values of the smallest 8 bits.

So, starting with 101111111111000, which is 24568 decimal, n&255 gives 11111000, which is 248 decimal.

Answered By: khelwood

To achieve this for a number x with n digits, one can use this


-2 to strip 0b, -8 to strip leftmost

Simply said it ands your number with just enough 1s that the 8 leftmost bits are set to 0.

Answered By: Jonathan R

another general way to do this is:

n = int('101111111111000', 2) # 24568

n & (1 << int.bit_length(n) - 8) - 1

gives 120 (or 1111000)

Answered By: Sam Mason

Another general way:


where x is the integer and n is the number of bits you want to strip.

Answered By: Adam JenĨa
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