How do you convert an 8-bit binary number to decimal?

Line the bits up under the position values 128-64-32-16-8-4-2-1, then add every position value that has a 1. Example: 11000000 = 128 + 64 = 192.

This is the everyday skill behind reading an IPv4 address or a subnet mask: each octet a router carries in binary, you read in decimal by summing the "on" position values. There's no arithmetic to memorize beyond the eight position values, since binary has only two digits — a position is either fully counted (bit = 1) or skipped (bit = 0).

Binary to Decimal Conversion:

1. Write the position values: 128, 64, 32, 16, 8, 4, 2, 1
2. Place the binary digits below their position values
3. Add the position values where the bit = 1

Example: 11000000

Result: 128 + 64 = 192

Go deeper:

• RapidTables — binary to decimal converter — type any pattern and watch the position-value sum; includes the formula and a lookup table.
• Wikipedia — Binary number § Binary to decimal — the general conversion algorithm behind the position-value method.