What are the required steps to convert base 10 integer
number -77 211 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:
|-77 211| = 77 211
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;
- 77 211 ÷ 2 = 38 605 + 1;
- 38 605 ÷ 2 = 19 302 + 1;
- 19 302 ÷ 2 = 9 651 + 0;
- 9 651 ÷ 2 = 4 825 + 1;
- 4 825 ÷ 2 = 2 412 + 1;
- 2 412 ÷ 2 = 1 206 + 0;
- 1 206 ÷ 2 = 603 + 0;
- 603 ÷ 2 = 301 + 1;
- 301 ÷ 2 = 150 + 1;
- 150 ÷ 2 = 75 + 0;
- 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.
77 211(10) = 1 0010 1101 1001 1011(2)
4. Determine the signed binary number bit length:
The base 2 number's actual length, in bits: 17.
- 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, 17,
3) so that the first bit (leftmost) could be zero
(we deal with a positive number at this moment)
=== is: 32.
5. Get the positive binary computer representation on 32 bits (4 Bytes):
If needed, add extra 0s in front (to the left) of the base 2 number, up to the required length, 32:
77 211(10) = 0000 0000 0000 0001 0010 1101 1001 1011
6. Get the negative integer number representation:
To get the negative integer number representation on 32 bits (4 Bytes),
... change the first bit (the leftmost), from 0 to 1...
-77 211(10) Base 10 integer number converted and written as a signed binary code (in base 2):
-77 211(10) = 1000 0000 0000 0001 0010 1101 1001 1011
Spaces were used to group digits: for binary, by 4, for decimal, by 3.