Binary numbers are all composed of 0 and 1

Binary number to 10: starting from the last digit, the column is 0, 1, 2. ...

The nth digit (0 or 1) is multiplied by the n power of 2 and then added.

For example, if the binary number is 100 to 10, the binary number is 0 × 2 0+0× 21+1× 2 2 = 4.