1. Is this a positive or a negative number?
1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1010 is the binary representation of a negative integer, on 64 bits (8 Bytes).
In a signed binary in two's complement representation, the first bit (the leftmost) indicates the sign, 1 = negative, 0 = positive.
2. Get the binary representation in one's complement.
* Run this step only if the number is negative *
Note on binary subtraction rules:
11 - 1 = 10; 10 - 1 = 1; 1 - 0 = 1; 1 - 1 = 0.
Subtract 1 from the initial binary number.
1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1010 - 1 = 1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1001
3. Get the binary representation of the positive (unsigned) number.
* Run this step only if the number is negative *
Flip all the bits of the signed binary in one's complement representation (reverse the digits) - replace the bits set on 1 with 0s and the bits on 0 with 1s:
!(1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1001) = 0011 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0110
4. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
263
0 262
0 261
1 260
1 259
0 258
0 257
0 256
0 255
0 254
0 253
0 252
0 251
0 250
0 249
0 248
0 247
0 246
0 245
0 244
0 243
0 242
0 241
0 240
0 239
0 238
0 237
0 236
0 235
0 234
0 233
0 232
0 231
0 230
0 229
0 228
0 227
0 226
0 225
0 224
0 223
0 222
0 221
0 220
0 219
0 218
0 217
0 216
0 215
0 214
0 213
0 212
0 211
0 210
0 29
0 28
0 27
0 26
0 25
1 24
0 23
0 22
1 21
1 20
0
5. Multiply each bit by its corresponding power of 2 and add all the terms up.
0011 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0010 0110(2) =
(0 × 263 + 0 × 262 + 1 × 261 + 1 × 260 + 0 × 259 + 0 × 258 + 0 × 257 + 0 × 256 + 0 × 255 + 0 × 254 + 0 × 253 + 0 × 252 + 0 × 251 + 0 × 250 + 0 × 249 + 0 × 248 + 0 × 247 + 0 × 246 + 0 × 245 + 0 × 244 + 0 × 243 + 0 × 242 + 0 × 241 + 0 × 240 + 0 × 239 + 0 × 238 + 0 × 237 + 0 × 236 + 0 × 235 + 0 × 234 + 0 × 233 + 0 × 232 + 0 × 231 + 0 × 230 + 0 × 229 + 0 × 228 + 0 × 227 + 0 × 226 + 0 × 225 + 0 × 224 + 0 × 223 + 0 × 222 + 0 × 221 + 0 × 220 + 0 × 219 + 0 × 218 + 0 × 217 + 0 × 216 + 0 × 215 + 0 × 214 + 0 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 0 × 29 + 0 × 28 + 0 × 27 + 0 × 26 + 1 × 25 + 0 × 24 + 0 × 23 + 1 × 22 + 1 × 21 + 0 × 20)(10) =
(0 + 0 + 2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 32 + 0 + 0 + 4 + 2 + 0)(10) =
(2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 32 + 4 + 2)(10) =
3 458 764 513 820 540 966(10)
6. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1010(2) = -3 458 764 513 820 540 966(10)
The signed binary number in two's complement representation 1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1010(2) converted and written as an integer in decimal system (base ten):
1100 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1111 1101 1010(2) = -3 458 764 513 820 540 966(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.