In a signed binary, the first bit (the leftmost) is reserved for the sign,
1 = negative, 0 = positive. This bit does not count when calculating the absolute value.
2. Construct the unsigned binary number.
Exclude the first bit (the leftmost), that is reserved for the sign:
0101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101 = 101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101
3. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
262
1 261
0 260
1 259
1 258
0 257
1 256
0 255
0 254
1 253
0 252
1 251
0 250
1 249
1 248
1 247
0 246
1 245
1 244
0 243
0 242
1 241
1 240
0 239
1 238
1 237
1 236
0 235
1 234
0 233
1 232
0 231
1 230
1 229
1 228
1 227
0 226
1 225
1 224
1 223
0 222
1 221
1 220
1 219
0 218
1 217
0 216
1 215
1 214
1 213
0 212
0 211
1 210
1 29
1 28
1 27
1 26
0 25
0 24
0 23
0 22
1 21
0 20
1
4. Multiply each bit by its corresponding power of 2 and add all the terms up.
101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101(2) =
(1 × 262 + 0 × 261 + 1 × 260 + 1 × 259 + 0 × 258 + 1 × 257 + 0 × 256 + 0 × 255 + 1 × 254 + 0 × 253 + 1 × 252 + 0 × 251 + 1 × 250 + 1 × 249 + 1 × 248 + 0 × 247 + 1 × 246 + 1 × 245 + 0 × 244 + 0 × 243 + 1 × 242 + 1 × 241 + 0 × 240 + 1 × 239 + 1 × 238 + 1 × 237 + 0 × 236 + 1 × 235 + 0 × 234 + 1 × 233 + 0 × 232 + 1 × 231 + 1 × 230 + 1 × 229 + 1 × 228 + 0 × 227 + 1 × 226 + 1 × 225 + 1 × 224 + 0 × 223 + 1 × 222 + 1 × 221 + 1 × 220 + 0 × 219 + 1 × 218 + 0 × 217 + 1 × 216 + 1 × 215 + 1 × 214 + 0 × 213 + 0 × 212 + 1 × 211 + 1 × 210 + 1 × 29 + 1 × 28 + 1 × 27 + 0 × 26 + 0 × 25 + 0 × 24 + 0 × 23 + 1 × 22 + 0 × 21 + 1 × 20)(10) =
(4 611 686 018 427 387 904 + 0 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 0 + 144 115 188 075 855 872 + 0 + 0 + 18 014 398 509 481 984 + 0 + 4 503 599 627 370 496 + 0 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 0 + 70 368 744 177 664 + 35 184 372 088 832 + 0 + 0 + 4 398 046 511 104 + 2 199 023 255 552 + 0 + 549 755 813 888 + 274 877 906 944 + 137 438 953 472 + 0 + 34 359 738 368 + 0 + 8 589 934 592 + 0 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 0 + 67 108 864 + 33 554 432 + 16 777 216 + 0 + 4 194 304 + 2 097 152 + 1 048 576 + 0 + 262 144 + 0 + 65 536 + 32 768 + 16 384 + 0 + 0 + 2 048 + 1 024 + 512 + 256 + 128 + 0 + 0 + 0 + 0 + 4 + 0 + 1)(10) =
(4 611 686 018 427 387 904 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 144 115 188 075 855 872 + 18 014 398 509 481 984 + 4 503 599 627 370 496 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 70 368 744 177 664 + 35 184 372 088 832 + 4 398 046 511 104 + 2 199 023 255 552 + 549 755 813 888 + 274 877 906 944 + 137 438 953 472 + 34 359 738 368 + 8 589 934 592 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 67 108 864 + 33 554 432 + 16 777 216 + 4 194 304 + 2 097 152 + 1 048 576 + 262 144 + 65 536 + 32 768 + 16 384 + 2 048 + 1 024 + 512 + 256 + 128 + 4 + 1)(10) =
6 509 784 945 747 414 917(10)
5. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
0101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101(2) = 6 509 784 945 747 414 917(10)
The number 0101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101(2) converted from a signed binary (base two) and written as an integer in decimal system (base ten):
0101 1010 0101 0111 0110 0110 1110 1010 1111 0111 0111 0101 1100 1111 1000 0101(2) = 6 509 784 945 747 414 917(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.