Convert 128 643 216 742 to a Signed Binary (Base 2)

How to convert 128 643 216 742(10), a signed base 10 integer number? How to write it as a signed binary code in base 2

What are the required steps to convert base 10 integer
number 128 643 216 742 to signed binary code (in base 2)?

  • 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.

Stop when you get a quotient that is equal to zero.


  • division = quotient + remainder;
  • 128 643 216 742 ÷ 2 = 64 321 608 371 + 0;
  • 64 321 608 371 ÷ 2 = 32 160 804 185 + 1;
  • 32 160 804 185 ÷ 2 = 16 080 402 092 + 1;
  • 16 080 402 092 ÷ 2 = 8 040 201 046 + 0;
  • 8 040 201 046 ÷ 2 = 4 020 100 523 + 0;
  • 4 020 100 523 ÷ 2 = 2 010 050 261 + 1;
  • 2 010 050 261 ÷ 2 = 1 005 025 130 + 1;
  • 1 005 025 130 ÷ 2 = 502 512 565 + 0;
  • 502 512 565 ÷ 2 = 251 256 282 + 1;
  • 251 256 282 ÷ 2 = 125 628 141 + 0;
  • 125 628 141 ÷ 2 = 62 814 070 + 1;
  • 62 814 070 ÷ 2 = 31 407 035 + 0;
  • 31 407 035 ÷ 2 = 15 703 517 + 1;
  • 15 703 517 ÷ 2 = 7 851 758 + 1;
  • 7 851 758 ÷ 2 = 3 925 879 + 0;
  • 3 925 879 ÷ 2 = 1 962 939 + 1;
  • 1 962 939 ÷ 2 = 981 469 + 1;
  • 981 469 ÷ 2 = 490 734 + 1;
  • 490 734 ÷ 2 = 245 367 + 0;
  • 245 367 ÷ 2 = 122 683 + 1;
  • 122 683 ÷ 2 = 61 341 + 1;
  • 61 341 ÷ 2 = 30 670 + 1;
  • 30 670 ÷ 2 = 15 335 + 0;
  • 15 335 ÷ 2 = 7 667 + 1;
  • 7 667 ÷ 2 = 3 833 + 1;
  • 3 833 ÷ 2 = 1 916 + 1;
  • 1 916 ÷ 2 = 958 + 0;
  • 958 ÷ 2 = 479 + 0;
  • 479 ÷ 2 = 239 + 1;
  • 239 ÷ 2 = 119 + 1;
  • 119 ÷ 2 = 59 + 1;
  • 59 ÷ 2 = 29 + 1;
  • 29 ÷ 2 = 14 + 1;
  • 14 ÷ 2 = 7 + 0;
  • 7 ÷ 2 = 3 + 1;
  • 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.

128 643 216 742(10) = 1 1101 1111 0011 1011 1011 1011 0101 0110 0110(2)


3. Determine the signed binary number bit length:

  • The base 2 number's actual length, in bits: 37.

  • 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) is reserved for 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, 37,

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:


128 643 216 742(10) Base 10 integer number converted and written as a signed binary code (in base 2):

128 643 216 742(10) = 0000 0000 0000 0000 0000 0000 0001 1101 1111 0011 1011 1011 1011 0101 0110 0110

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

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How to convert signed base 10 integers in decimal to binary code system

Follow the steps below to convert a signed base ten integer number to signed binary:

  • 1. In a signed binary, first bit (the leftmost) is reserved for sign: 0 = positive integer number, 1 = positive integer number. If the number to be converted is negative, start with its positive version.
  • 2. Divide repeatedly by 2 the positive integer number keeping track of each remainder. STOP when 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 have a length of 4, 8, 16, 32, 64, ... bits (power of 2) - if needed, fill in extra '0' bits in front of the base 2 number (to the left), up to the right length; this way the first bit (the leftmost one) is always '0', as for a positive representation.
  • 5. To get the negative reprezentation of the number, simply switch the first bit (the leftmost one), from '0' to '1'.

Example: convert the negative number -63 from decimal system (base ten) to signed binary code system:

  • 1. Start with the positive version of the number: |-63| = 63;
  • 2. Divide repeatedly 63 by 2, keeping track of each remainder, until we get a quotient that is equal to zero:
    • division = quotient + remainder
    • 63 ÷ 2 = 31 + 1
    • 31 ÷ 2 = 15 + 1
    • 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:
    63(10) = 11 1111(2)
  • 4. The actual length of base 2 representation number is 6, so the positive binary computer representation length of the signed binary will take in this case 8 bits (the least power of 2 higher than 6) - add extra '0's in front (to the left), up to the required length; this way the first bit (the leftmost one) is to be '0', as for a positive number:
    63(10) = 0011 1111(2)
  • 5. To get the negative integer number representation simply change the first bit (the leftmost), from '0' to '1':
    -63(10) = 1011 1111
  • Number -63(10), signed integer, converted from decimal system (base 10) to signed binary = 1011 1111