2. Multiply each bit by its corresponding power of 2 and add all the terms up.
1111 1111 1111 1011 0100 0000 0111 1000 1111 0001 1100 1100 0110 0010 1110 0111(2) =
(1 × 263 + 1 × 262 + 1 × 261 + 1 × 260 + 1 × 259 + 1 × 258 + 1 × 257 + 1 × 256 + 1 × 255 + 1 × 254 + 1 × 253 + 1 × 252 + 1 × 251 + 0 × 250 + 1 × 249 + 1 × 248 + 0 × 247 + 1 × 246 + 0 × 245 + 0 × 244 + 0 × 243 + 0 × 242 + 0 × 241 + 0 × 240 + 0 × 239 + 1 × 238 + 1 × 237 + 1 × 236 + 1 × 235 + 0 × 234 + 0 × 233 + 0 × 232 + 1 × 231 + 1 × 230 + 1 × 229 + 1 × 228 + 0 × 227 + 0 × 226 + 0 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 0 × 221 + 0 × 220 + 1 × 219 + 1 × 218 + 0 × 217 + 0 × 216 + 0 × 215 + 1 × 214 + 1 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 1 × 29 + 0 × 28 + 1 × 27 + 1 × 26 + 1 × 25 + 0 × 24 + 0 × 23 + 1 × 22 + 1 × 21 + 1 × 20)(10) =
(9 223 372 036 854 775 808 + 4 611 686 018 427 387 904 + 2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 288 230 376 151 711 744 + 144 115 188 075 855 872 + 72 057 594 037 927 936 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 9 007 199 254 740 992 + 4 503 599 627 370 496 + 2 251 799 813 685 248 + 0 + 562 949 953 421 312 + 281 474 976 710 656 + 0 + 70 368 744 177 664 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 0 + 0 + 0 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 0 + 0 + 0 + 16 777 216 + 8 388 608 + 4 194 304 + 0 + 0 + 524 288 + 262 144 + 0 + 0 + 0 + 16 384 + 8 192 + 0 + 0 + 0 + 512 + 0 + 128 + 64 + 32 + 0 + 0 + 4 + 2 + 1)(10) =
(9 223 372 036 854 775 808 + 4 611 686 018 427 387 904 + 2 305 843 009 213 693 952 + 1 152 921 504 606 846 976 + 576 460 752 303 423 488 + 288 230 376 151 711 744 + 144 115 188 075 855 872 + 72 057 594 037 927 936 + 36 028 797 018 963 968 + 18 014 398 509 481 984 + 9 007 199 254 740 992 + 4 503 599 627 370 496 + 2 251 799 813 685 248 + 562 949 953 421 312 + 281 474 976 710 656 + 70 368 744 177 664 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 34 359 738 368 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 16 777 216 + 8 388 608 + 4 194 304 + 524 288 + 262 144 + 16 384 + 8 192 + 512 + 128 + 64 + 32 + 4 + 2 + 1)(10) =
18 445 407 587 022 955 239(10)
The number 1111 1111 1111 1011 0100 0000 0111 1000 1111 0001 1100 1100 0110 0010 1110 0111(2) converted from an unsigned binary (in base 2) and written as a positive integer (with no sign) in decimal system (in base ten):
1111 1111 1111 1011 0100 0000 0111 1000 1111 0001 1100 1100 0110 0010 1110 0111(2) = 18 445 407 587 022 955 239(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.