2. Multiply each bit by its corresponding power of 2 and add all the terms up.
100 0000 0000 1000 0010 0001 1011(2) =
(1 × 226 + 0 × 225 + 0 × 224 + 0 × 223 + 0 × 222 + 0 × 221 + 0 × 220 + 0 × 219 + 0 × 218 + 0 × 217 + 0 × 216 + 1 × 215 + 0 × 214 + 0 × 213 + 0 × 212 + 0 × 211 + 0 × 210 + 1 × 29 + 0 × 28 + 0 × 27 + 0 × 26 + 0 × 25 + 1 × 24 + 1 × 23 + 0 × 22 + 1 × 21 + 1 × 20)(10) =
(67 108 864 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 32 768 + 0 + 0 + 0 + 0 + 0 + 512 + 0 + 0 + 0 + 0 + 16 + 8 + 0 + 2 + 1)(10) =
(67 108 864 + 32 768 + 512 + 16 + 8 + 2 + 1)(10) =
67 142 171(10)
The number 100 0000 0000 1000 0010 0001 1011(2) converted from an unsigned binary (in base 2) and written as a positive integer (with no sign) in decimal system (in base ten):
100 0000 0000 1000 0010 0001 1011(2) = 67 142 171(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.