Two’s Complement of 101101121011011_2

Two’s Complement of 101101121011011_2

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Nov 4, 2026

To find the two’s complement of a binary number, the standard procedure is: [bitwise inversion]{def="Flipping each bit (0↔1)} then add 1; the result represents the negation under a fixed bit-width. This course section demonstrates the computation for 101101121011011_2 (a 7-bit value).

Note: Two’s complement is defined with respect to an nn-bit width. Here, we treat 10110111011011 as exactly 7 bits, since no other width is specified.

Two's Complement (Inverting Bits and Adding 1)

Key concepts used here:

  • two’s complement
  • bit-width
  • bitwise inversion
  • LSB

Because the bit-width controls the interpretation and overflow behavior, we compute the two’s complement using the same 7 bits as the given number.

Compute the two’s complement of $1011011$

  1. 1
    Step 1

    Use 7 bits because the input has 7 digits: n=7n=7.

  2. 2
    Step 2

    Change 1→01\to 0 and 0→10\to 1: 1011011→01001001011011 \rightarrow 0100100.

  3. 3
    Step 3

    Compute 0100100+1=01001010100100 + 1 = 0100101.

  4. 4
    Step 4

    Therefore, the two’s complement of 101101121011011_2 is 010010120100101_2.

We can also verify the negation property in 7 bits: 10110112+01001012=1000000021011011_2 + 0100101_2 = 10000000_2 The sum equals 272^7, which becomes 000000020000000_2 when only 7 bits are kept—consistent with two’s complement modulo arithmetic for n=7n=7.

Pro Tip: Don’t guess the bit-width

If a question gives a binary string with no width, use its length as nn. Changing nn changes the two’s complement result.

Overflow / carry matters

When you add the final +1+1, you may get a carry out of the MSB; with fixed nn bits, that carry is dropped (mod 2n2^n).

Bit transformation from 10110111011011 to its two’s complement

Shows each stage aligned per bit position (MSB → LSB).

Common checks and extensions

Two’s Complement Quick Deck

1 / 4
Question · Term

What is the standard method to compute two’s complement of a binary number?

Click to reveal
Answer · Definition

Invert all bits, then add 1 (for a fixed bit-width nn).

Knowledge Check

Question 1 of 4
Q1Single choice

What is the two’s complement of 101101121011011_2 (using 7 bits)?