Convert 111 111 111 111 111 768 to a Signed Binary in Two's (2's) Complement Representation

How to convert decimal number 111 111 111 111 111 768(10) to a signed binary in two's (2's) complement representation

What are the steps to convert decimal number
111 111 111 111 111 768 to a signed binary in two's (2's) complement representation?

  • A signed integer, written in base ten, or a decimal system number, is a number written using the digits 0 through 9 and the sign, which can be positive (+) or negative (-). If positive, the sign is usually not written. A number written in base two, or binary, is a number written using only the digits 0 and 1.

1. Divide the number repeatedly by 2:

Keep track of each remainder.

We stop when we get a quotient that is equal to zero.


  • division = quotient + remainder;
  • 111 111 111 111 111 768 ÷ 2 = 55 555 555 555 555 884 + 0;
  • 55 555 555 555 555 884 ÷ 2 = 27 777 777 777 777 942 + 0;
  • 27 777 777 777 777 942 ÷ 2 = 13 888 888 888 888 971 + 0;
  • 13 888 888 888 888 971 ÷ 2 = 6 944 444 444 444 485 + 1;
  • 6 944 444 444 444 485 ÷ 2 = 3 472 222 222 222 242 + 1;
  • 3 472 222 222 222 242 ÷ 2 = 1 736 111 111 111 121 + 0;
  • 1 736 111 111 111 121 ÷ 2 = 868 055 555 555 560 + 1;
  • 868 055 555 555 560 ÷ 2 = 434 027 777 777 780 + 0;
  • 434 027 777 777 780 ÷ 2 = 217 013 888 888 890 + 0;
  • 217 013 888 888 890 ÷ 2 = 108 506 944 444 445 + 0;
  • 108 506 944 444 445 ÷ 2 = 54 253 472 222 222 + 1;
  • 54 253 472 222 222 ÷ 2 = 27 126 736 111 111 + 0;
  • 27 126 736 111 111 ÷ 2 = 13 563 368 055 555 + 1;
  • 13 563 368 055 555 ÷ 2 = 6 781 684 027 777 + 1;
  • 6 781 684 027 777 ÷ 2 = 3 390 842 013 888 + 1;
  • 3 390 842 013 888 ÷ 2 = 1 695 421 006 944 + 0;
  • 1 695 421 006 944 ÷ 2 = 847 710 503 472 + 0;
  • 847 710 503 472 ÷ 2 = 423 855 251 736 + 0;
  • 423 855 251 736 ÷ 2 = 211 927 625 868 + 0;
  • 211 927 625 868 ÷ 2 = 105 963 812 934 + 0;
  • 105 963 812 934 ÷ 2 = 52 981 906 467 + 0;
  • 52 981 906 467 ÷ 2 = 26 490 953 233 + 1;
  • 26 490 953 233 ÷ 2 = 13 245 476 616 + 1;
  • 13 245 476 616 ÷ 2 = 6 622 738 308 + 0;
  • 6 622 738 308 ÷ 2 = 3 311 369 154 + 0;
  • 3 311 369 154 ÷ 2 = 1 655 684 577 + 0;
  • 1 655 684 577 ÷ 2 = 827 842 288 + 1;
  • 827 842 288 ÷ 2 = 413 921 144 + 0;
  • 413 921 144 ÷ 2 = 206 960 572 + 0;
  • 206 960 572 ÷ 2 = 103 480 286 + 0;
  • 103 480 286 ÷ 2 = 51 740 143 + 0;
  • 51 740 143 ÷ 2 = 25 870 071 + 1;
  • 25 870 071 ÷ 2 = 12 935 035 + 1;
  • 12 935 035 ÷ 2 = 6 467 517 + 1;
  • 6 467 517 ÷ 2 = 3 233 758 + 1;
  • 3 233 758 ÷ 2 = 1 616 879 + 0;
  • 1 616 879 ÷ 2 = 808 439 + 1;
  • 808 439 ÷ 2 = 404 219 + 1;
  • 404 219 ÷ 2 = 202 109 + 1;
  • 202 109 ÷ 2 = 101 054 + 1;
  • 101 054 ÷ 2 = 50 527 + 0;
  • 50 527 ÷ 2 = 25 263 + 1;
  • 25 263 ÷ 2 = 12 631 + 1;
  • 12 631 ÷ 2 = 6 315 + 1;
  • 6 315 ÷ 2 = 3 157 + 1;
  • 3 157 ÷ 2 = 1 578 + 1;
  • 1 578 ÷ 2 = 789 + 0;
  • 789 ÷ 2 = 394 + 1;
  • 394 ÷ 2 = 197 + 0;
  • 197 ÷ 2 = 98 + 1;
  • 98 ÷ 2 = 49 + 0;
  • 49 ÷ 2 = 24 + 1;
  • 24 ÷ 2 = 12 + 0;
  • 12 ÷ 2 = 6 + 0;
  • 6 ÷ 2 = 3 + 0;
  • 3 ÷ 2 = 1 + 1;
  • 1 ÷ 2 = 0 + 1;

2. Construct the base 2 representation of the positive number:

Take all the remainders starting from the bottom of the list constructed above.

111 111 111 111 111 768(10) = 1 1000 1010 1011 1110 1111 0111 1000 0100 0110 0000 0111 0100 0101 1000(2)

3. Determine the signed binary number bit length:

  • The base 2 number's actual length, in bits: 57.

  • A signed binary's bit length must be equal to a power of 2, as of:
  • 21 = 2; 22 = 4; 23 = 8; 24 = 16; 25 = 32; 26 = 64; ...
  • The first bit (the leftmost) indicates the sign:
  • 0 = positive integer number, 1 = negative integer number

The least number that is:


1) a power of 2

2) and is larger than the actual length, 57,

3) so that the first bit (leftmost) could be zero
(we deal with a positive number at this moment)


=== is: 64.


4. Get the positive binary computer representation on 64 bits (8 Bytes):

If needed, add extra 0s in front (to the left) of the base 2 number, up to the required length, 64.


Decimal Number 111 111 111 111 111 768(10) converted to signed binary in two's complement representation:

111 111 111 111 111 768(10) = 0000 0001 1000 1010 1011 1110 1111 0111 1000 0100 0110 0000 0111 0100 0101 1000

Spaces were used to group digits: for binary, by 4, for decimal, by 3.


How to convert signed integers from decimal system to signed binary in two's complement representation

Follow the steps below to convert a signed base 10 integer number to signed binary in two's complement representation:

  • 1. If the number to be converted is negative, start with the positive version of the number.
  • 2. Divide repeatedly by 2 the positive representation of the integer number, keeping track of each remainder, until we get a quotient that is zero.
  • 3. Construct the base 2 representation of the positive number, by taking all the remainders starting from the bottom of the list constructed above. Thus, the last remainder of the divisions becomes the first symbol (the leftmost) of the base two number, while the first remainder becomes the last symbol (the rightmost).
  • 4. Binary numbers represented in computer language must have 4, 8, 16, 32, 64, ... bit length (a power of 2) - if needed, add extra bits on 0 in front (to the left) of the base 2 number above, up to the required length, so that the first bit (the leftmost) will be 0, correctly representing a positive number.
  • 5. To get the negative integer number representation in signed binary one's complement, replace all 0 bits with 1s and all 1 bits with 0s (reversing the digits).
  • 6. To get the negative integer number, in signed binary two's complement representation, add 1 to the number above.

Example: convert the negative number -60 from the decimal system (base ten) to signed binary in two's complement:

  • 1. Start with the positive version of the number: |-60| = 60
  • 2. Divide repeatedly 60 by 2, keeping track of each remainder:
    • division = quotient + remainder
    • 60 ÷ 2 = 30 + 0
    • 30 ÷ 2 = 15 + 0
    • 15 ÷ 2 = 7 + 1
    • 7 ÷ 2 = 3 + 1
    • 3 ÷ 2 = 1 + 1
    • 1 ÷ 2 = 0 + 1
  • 3. Construct the base 2 representation of the positive number, by taking all the remainders starting from the bottom of the list constructed above:
    60(10) = 11 1100(2)
  • 4. Bit length of base 2 representation number is 6, so the positive binary computer representation of a signed binary will take in this particular case 8 bits (the least power of 2 larger than 6) - add extra 0 digits in front of the base 2 number, up to the required length:
    60(10) = 0011 1100(2)
  • 5. To get the negative integer number representation in signed binary one's complement, replace all the 0 bits with 1s and all 1 bits with 0s (reversing the digits):
    !(0011 1100) = 1100 0011
  • 6. To get the negative integer number, signed binary in two's complement representation, add 1 to the number above:
    -60(10) = 1100 0011 + 1 = 1100 0100
  • Number -60(10), signed integer, converted from decimal system (base 10) to signed binary two's complement representation = 1100 0100