2. Multiply each bit by its corresponding power of 2 and add all the terms up.
1111 0001 1111 1000 1111 0101 1111 0110 0000 0001(2) =
(1 × 239 + 1 × 238 + 1 × 237 + 1 × 236 + 0 × 235 + 0 × 234 + 0 × 233 + 1 × 232 + 1 × 231 + 1 × 230 + 1 × 229 + 1 × 228 + 1 × 227 + 0 × 226 + 0 × 225 + 0 × 224 + 1 × 223 + 1 × 222 + 1 × 221 + 1 × 220 + 0 × 219 + 1 × 218 + 0 × 217 + 1 × 216 + 1 × 215 + 1 × 214 + 1 × 213 + 1 × 212 + 0 × 211 + 1 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 0 × 26 + 0 × 25 + 0 × 24 + 0 × 23 + 0 × 22 + 0 × 21 + 1 × 20)(10) =
(549 755 813 888 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 0 + 0 + 0 + 4 294 967 296 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 134 217 728 + 0 + 0 + 0 + 8 388 608 + 4 194 304 + 2 097 152 + 1 048 576 + 0 + 262 144 + 0 + 65 536 + 32 768 + 16 384 + 8 192 + 4 096 + 0 + 1 024 + 512 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 1)(10) =
(549 755 813 888 + 274 877 906 944 + 137 438 953 472 + 68 719 476 736 + 4 294 967 296 + 2 147 483 648 + 1 073 741 824 + 536 870 912 + 268 435 456 + 134 217 728 + 8 388 608 + 4 194 304 + 2 097 152 + 1 048 576 + 262 144 + 65 536 + 32 768 + 16 384 + 8 192 + 4 096 + 1 024 + 512 + 1)(10) =
1 039 263 987 201(10)
The number 1111 0001 1111 1000 1111 0101 1111 0110 0000 0001(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 0001 1111 1000 1111 0101 1111 0110 0000 0001(2) = 1 039 263 987 201(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.