2. Multiply each bit by its corresponding power of 2 and add all the terms up.
1111 0101 1101 1010 0100 0010 0101 1101 0110 0011 1110 0000 0001(2) =
(1 × 251 + 1 × 250 + 1 × 249 + 1 × 248 + 0 × 247 + 1 × 246 + 0 × 245 + 1 × 244 + 1 × 243 + 1 × 242 + 0 × 241 + 1 × 240 + 1 × 239 + 0 × 238 + 1 × 237 + 0 × 236 + 0 × 235 + 1 × 234 + 0 × 233 + 0 × 232 + 0 × 231 + 0 × 230 + 1 × 229 + 0 × 228 + 0 × 227 + 1 × 226 + 0 × 225 + 1 × 224 + 1 × 223 + 1 × 222 + 0 × 221 + 1 × 220 + 0 × 219 + 1 × 218 + 1 × 217 + 0 × 216 + 0 × 215 + 0 × 214 + 1 × 213 + 1 × 212 + 1 × 211 + 1 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 0 × 26 + 0 × 25 + 0 × 24 + 0 × 23 + 0 × 22 + 0 × 21 + 1 × 20)(10) =
(2 251 799 813 685 248 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 0 + 70 368 744 177 664 + 0 + 17 592 186 044 416 + 8 796 093 022 208 + 4 398 046 511 104 + 0 + 1 099 511 627 776 + 549 755 813 888 + 0 + 137 438 953 472 + 0 + 0 + 17 179 869 184 + 0 + 0 + 0 + 0 + 536 870 912 + 0 + 0 + 67 108 864 + 0 + 16 777 216 + 8 388 608 + 4 194 304 + 0 + 1 048 576 + 0 + 262 144 + 131 072 + 0 + 0 + 0 + 8 192 + 4 096 + 2 048 + 1 024 + 512 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 1)(10) =
(2 251 799 813 685 248 + 1 125 899 906 842 624 + 562 949 953 421 312 + 281 474 976 710 656 + 70 368 744 177 664 + 17 592 186 044 416 + 8 796 093 022 208 + 4 398 046 511 104 + 1 099 511 627 776 + 549 755 813 888 + 137 438 953 472 + 17 179 869 184 + 536 870 912 + 67 108 864 + 16 777 216 + 8 388 608 + 4 194 304 + 1 048 576 + 262 144 + 131 072 + 8 192 + 4 096 + 2 048 + 1 024 + 512 + 1)(10) =
4 325 084 241 477 121(10)
The number 1111 0101 1101 1010 0100 0010 0101 1101 0110 0011 1110 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 0101 1101 1010 0100 0010 0101 1101 0110 0011 1110 0000 0001(2) = 4 325 084 241 477 121(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.