To convert a binary number to decimal, find the sum of each digit multiplied by its place value in base 2, where the rightmost digit is 20 and each place value doubles moving left. For example, to convert 1011 to decimal: 1*8 + 0*4 + 1*2 + 1*1 = 8 + 0 + 2 + 1 = 11, so the decimal equivalent of 1011 in binary is 11 in decimal.