Convert 100 100 111 010 665 to a Signed Binary in Two's (2's) Complement Representation

How to convert decimal number 100 100 111 010 665(10) to a signed binary in two's (2's) complement representation

What are the steps to convert decimal number
100 100 111 010 665 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;
  • 100 100 111 010 665 ÷ 2 = 50 050 055 505 332 + 1;
  • 50 050 055 505 332 ÷ 2 = 25 025 027 752 666 + 0;
  • 25 025 027 752 666 ÷ 2 = 12 512 513 876 333 + 0;
  • 12 512 513 876 333 ÷ 2 = 6 256 256 938 166 + 1;
  • 6 256 256 938 166 ÷ 2 = 3 128 128 469 083 + 0;
  • 3 128 128 469 083 ÷ 2 = 1 564 064 234 541 + 1;
  • 1 564 064 234 541 ÷ 2 = 782 032 117 270 + 1;
  • 782 032 117 270 ÷ 2 = 391 016 058 635 + 0;
  • 391 016 058 635 ÷ 2 = 195 508 029 317 + 1;
  • 195 508 029 317 ÷ 2 = 97 754 014 658 + 1;
  • 97 754 014 658 ÷ 2 = 48 877 007 329 + 0;
  • 48 877 007 329 ÷ 2 = 24 438 503 664 + 1;
  • 24 438 503 664 ÷ 2 = 12 219 251 832 + 0;
  • 12 219 251 832 ÷ 2 = 6 109 625 916 + 0;
  • 6 109 625 916 ÷ 2 = 3 054 812 958 + 0;
  • 3 054 812 958 ÷ 2 = 1 527 406 479 + 0;
  • 1 527 406 479 ÷ 2 = 763 703 239 + 1;
  • 763 703 239 ÷ 2 = 381 851 619 + 1;
  • 381 851 619 ÷ 2 = 190 925 809 + 1;
  • 190 925 809 ÷ 2 = 95 462 904 + 1;
  • 95 462 904 ÷ 2 = 47 731 452 + 0;
  • 47 731 452 ÷ 2 = 23 865 726 + 0;
  • 23 865 726 ÷ 2 = 11 932 863 + 0;
  • 11 932 863 ÷ 2 = 5 966 431 + 1;
  • 5 966 431 ÷ 2 = 2 983 215 + 1;
  • 2 983 215 ÷ 2 = 1 491 607 + 1;
  • 1 491 607 ÷ 2 = 745 803 + 1;
  • 745 803 ÷ 2 = 372 901 + 1;
  • 372 901 ÷ 2 = 186 450 + 1;
  • 186 450 ÷ 2 = 93 225 + 0;
  • 93 225 ÷ 2 = 46 612 + 1;
  • 46 612 ÷ 2 = 23 306 + 0;
  • 23 306 ÷ 2 = 11 653 + 0;
  • 11 653 ÷ 2 = 5 826 + 1;
  • 5 826 ÷ 2 = 2 913 + 0;
  • 2 913 ÷ 2 = 1 456 + 1;
  • 1 456 ÷ 2 = 728 + 0;
  • 728 ÷ 2 = 364 + 0;
  • 364 ÷ 2 = 182 + 0;
  • 182 ÷ 2 = 91 + 0;
  • 91 ÷ 2 = 45 + 1;
  • 45 ÷ 2 = 22 + 1;
  • 22 ÷ 2 = 11 + 0;
  • 11 ÷ 2 = 5 + 1;
  • 5 ÷ 2 = 2 + 1;
  • 2 ÷ 2 = 1 + 0;
  • 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.

100 100 111 010 665(10) = 101 1011 0000 1010 0101 1111 1000 1111 0000 1011 0110 1001(2)

3. Determine the signed binary number bit length:

  • The base 2 number's actual length, in bits: 47.

  • 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, 47,

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 100 100 111 010 665(10) converted to signed binary in two's complement representation:

100 100 111 010 665(10) = 0000 0000 0000 0000 0101 1011 0000 1010 0101 1111 1000 1111 0000 1011 0110 1001

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