What are the required steps to convert base 10 integer
number -42 949 666 793 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:
|-42 949 666 793| = 42 949 666 793
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;
- 42 949 666 793 ÷ 2 = 21 474 833 396 + 1;
- 21 474 833 396 ÷ 2 = 10 737 416 698 + 0;
- 10 737 416 698 ÷ 2 = 5 368 708 349 + 0;
- 5 368 708 349 ÷ 2 = 2 684 354 174 + 1;
- 2 684 354 174 ÷ 2 = 1 342 177 087 + 0;
- 1 342 177 087 ÷ 2 = 671 088 543 + 1;
- 671 088 543 ÷ 2 = 335 544 271 + 1;
- 335 544 271 ÷ 2 = 167 772 135 + 1;
- 167 772 135 ÷ 2 = 83 886 067 + 1;
- 83 886 067 ÷ 2 = 41 943 033 + 1;
- 41 943 033 ÷ 2 = 20 971 516 + 1;
- 20 971 516 ÷ 2 = 10 485 758 + 0;
- 10 485 758 ÷ 2 = 5 242 879 + 0;
- 5 242 879 ÷ 2 = 2 621 439 + 1;
- 2 621 439 ÷ 2 = 1 310 719 + 1;
- 1 310 719 ÷ 2 = 655 359 + 1;
- 655 359 ÷ 2 = 327 679 + 1;
- 327 679 ÷ 2 = 163 839 + 1;
- 163 839 ÷ 2 = 81 919 + 1;
- 81 919 ÷ 2 = 40 959 + 1;
- 40 959 ÷ 2 = 20 479 + 1;
- 20 479 ÷ 2 = 10 239 + 1;
- 10 239 ÷ 2 = 5 119 + 1;
- 5 119 ÷ 2 = 2 559 + 1;
- 2 559 ÷ 2 = 1 279 + 1;
- 1 279 ÷ 2 = 639 + 1;
- 639 ÷ 2 = 319 + 1;
- 319 ÷ 2 = 159 + 1;
- 159 ÷ 2 = 79 + 1;
- 79 ÷ 2 = 39 + 1;
- 39 ÷ 2 = 19 + 1;
- 19 ÷ 2 = 9 + 1;
- 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.
42 949 666 793(10) = 1001 1111 1111 1111 1111 1110 0111 1110 1001(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:
42 949 666 793(10) = 0000 0000 0000 0000 0000 0000 0000 1001 1111 1111 1111 1111 1110 0111 1110 1001
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...
-42 949 666 793(10) Base 10 integer number converted and written as a signed binary code (in base 2):
-42 949 666 793(10) = 1000 0000 0000 0000 0000 0000 0000 1001 1111 1111 1111 1111 1110 0111 1110 1001
Spaces were used to group digits: for binary, by 4, for decimal, by 3.