In a signed binary in one's complement representation, the first bit (the leftmost) indicates the sign, 1 = negative, 0 = positive.
2. 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:
* Not the case - the number is positive *
3. 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
0 259
0 258
1 257
0 256
1 255
0 254
1 253
0 252
1 251
0 250
0 249
1 248
0 247
1 246
0 245
1 244
0 243
0 242
1 241
0 240
1 239
0 238
1 237
0 236
0 235
0 234
1 233
0 232
1 231
0 230
1 229
0 228
1 227
0 226
0 225
1 224
0 223
0 222
1 221
0 220
1 219
0 218
0 217
1 216
0 215
1 214
0 213
0 212
1 211
0 210
1 29
0 28
0 27
1 26
0 25
1 24
0 23
0 22
0 21
1 20
1
4. Multiply each bit by its corresponding power of 2 and add all the terms up.
0010 0101 0101 0010 1010 0101 0100 0101 0101 0010 0101 0010 1001 0100 1010 0011(2) =
(0 × 263 + 0 × 262 + 1 × 261 + 0 × 260 + 0 × 259 + 1 × 258 + 0 × 257 + 1 × 256 + 0 × 255 + 1 × 254 + 0 × 253 + 1 × 252 + 0 × 251 + 0 × 250 + 1 × 249 + 0 × 248 + 1 × 247 + 0 × 246 + 1 × 245 + 0 × 244 + 0 × 243 + 1 × 242 + 0 × 241 + 1 × 240 + 0 × 239 + 1 × 238 + 0 × 237 + 0 × 236 + 0 × 235 + 1 × 234 + 0 × 233 + 1 × 232 + 0 × 231 + 1 × 230 + 0 × 229 + 1 × 228 + 0 × 227 + 0 × 226 + 1 × 225 + 0 × 224 + 0 × 223 + 1 × 222 + 0 × 221 + 1 × 220 + 0 × 219 + 0 × 218 + 1 × 217 + 0 × 216 + 1 × 215 + 0 × 214 + 0 × 213 + 1 × 212 + 0 × 211 + 1 × 210 + 0 × 29 + 0 × 28 + 1 × 27 + 0 × 26 + 1 × 25 + 0 × 24 + 0 × 23 + 0 × 22 + 1 × 21 + 1 × 20)(10) =
(0 + 0 + 2 305 843 009 213 693 952 + 0 + 0 + 288 230 376 151 711 744 + 0 + 72 057 594 037 927 936 + 0 + 18 014 398 509 481 984 + 0 + 4 503 599 627 370 496 + 0 + 0 + 562 949 953 421 312 + 0 + 140 737 488 355 328 + 0 + 35 184 372 088 832 + 0 + 0 + 4 398 046 511 104 + 0 + 1 099 511 627 776 + 0 + 274 877 906 944 + 0 + 0 + 0 + 17 179 869 184 + 0 + 4 294 967 296 + 0 + 1 073 741 824 + 0 + 268 435 456 + 0 + 0 + 33 554 432 + 0 + 0 + 4 194 304 + 0 + 1 048 576 + 0 + 0 + 131 072 + 0 + 32 768 + 0 + 0 + 4 096 + 0 + 1 024 + 0 + 0 + 128 + 0 + 32 + 0 + 0 + 0 + 2 + 1)(10) =
(2 305 843 009 213 693 952 + 288 230 376 151 711 744 + 72 057 594 037 927 936 + 18 014 398 509 481 984 + 4 503 599 627 370 496 + 562 949 953 421 312 + 140 737 488 355 328 + 35 184 372 088 832 + 4 398 046 511 104 + 1 099 511 627 776 + 274 877 906 944 + 17 179 869 184 + 4 294 967 296 + 1 073 741 824 + 268 435 456 + 33 554 432 + 4 194 304 + 1 048 576 + 131 072 + 32 768 + 4 096 + 1 024 + 128 + 32 + 2 + 1)(10) =
2 689 393 644 646 077 603(10)
5. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0010 0101 0101 0010 1010 0101 0100 0101 0101 0010 0101 0010 1001 0100 1010 0011(2) = 2 689 393 644 646 077 603(10)
The signed binary number in one's complement representation 0010 0101 0101 0010 1010 0101 0100 0101 0101 0010 0101 0010 1001 0100 1010 0011(2) converted and written as an integer in decimal system (base ten):
0010 0101 0101 0010 1010 0101 0100 0101 0101 0010 0101 0010 1001 0100 1010 0011(2) = 2 689 393 644 646 077 603(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.