Convert -40 728 821 789 to a Signed Binary (Base 2)

How to convert -40 728 821 789(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 -40 728 821 789 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. Start with the positive version of the number:

|-40 728 821 789| = 40 728 821 789

2. 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;
  • 40 728 821 789 ÷ 2 = 20 364 410 894 + 1;
  • 20 364 410 894 ÷ 2 = 10 182 205 447 + 0;
  • 10 182 205 447 ÷ 2 = 5 091 102 723 + 1;
  • 5 091 102 723 ÷ 2 = 2 545 551 361 + 1;
  • 2 545 551 361 ÷ 2 = 1 272 775 680 + 1;
  • 1 272 775 680 ÷ 2 = 636 387 840 + 0;
  • 636 387 840 ÷ 2 = 318 193 920 + 0;
  • 318 193 920 ÷ 2 = 159 096 960 + 0;
  • 159 096 960 ÷ 2 = 79 548 480 + 0;
  • 79 548 480 ÷ 2 = 39 774 240 + 0;
  • 39 774 240 ÷ 2 = 19 887 120 + 0;
  • 19 887 120 ÷ 2 = 9 943 560 + 0;
  • 9 943 560 ÷ 2 = 4 971 780 + 0;
  • 4 971 780 ÷ 2 = 2 485 890 + 0;
  • 2 485 890 ÷ 2 = 1 242 945 + 0;
  • 1 242 945 ÷ 2 = 621 472 + 1;
  • 621 472 ÷ 2 = 310 736 + 0;
  • 310 736 ÷ 2 = 155 368 + 0;
  • 155 368 ÷ 2 = 77 684 + 0;
  • 77 684 ÷ 2 = 38 842 + 0;
  • 38 842 ÷ 2 = 19 421 + 0;
  • 19 421 ÷ 2 = 9 710 + 1;
  • 9 710 ÷ 2 = 4 855 + 0;
  • 4 855 ÷ 2 = 2 427 + 1;
  • 2 427 ÷ 2 = 1 213 + 1;
  • 1 213 ÷ 2 = 606 + 1;
  • 606 ÷ 2 = 303 + 0;
  • 303 ÷ 2 = 151 + 1;
  • 151 ÷ 2 = 75 + 1;
  • 75 ÷ 2 = 37 + 1;
  • 37 ÷ 2 = 18 + 1;
  • 18 ÷ 2 = 9 + 0;
  • 9 ÷ 2 = 4 + 1;
  • 4 ÷ 2 = 2 + 0;
  • 2 ÷ 2 = 1 + 0;
  • 1 ÷ 2 = 0 + 1;

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

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

40 728 821 789(10) = 1001 0111 1011 1010 0000 1000 0000 0001 1101(2)


4. Determine the signed binary number bit length:

  • The base 2 number's actual length, in bits: 36.

  • 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, 36,

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

=== is: 64.


5. 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:


40 728 821 789(10) = 0000 0000 0000 0000 0000 0000 0000 1001 0111 1011 1010 0000 1000 0000 0001 1101

6. Get the negative integer number representation:

To get the negative integer number representation on 64 bits (8 Bytes),

... change the first bit (the leftmost), from 0 to 1...


-40 728 821 789(10) Base 10 integer number converted and written as a signed binary code (in base 2):

-40 728 821 789(10) = 1000 0000 0000 0000 0000 0000 0000 1001 0111 1011 1010 0000 1000 0000 0001 1101

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