The pattern in the series is based on the difference between consecutive terms: \[ 6 - 2 = 4, \, 12 - 6 = 6, \, 20 - 12 = 8. \] The differences are increasing by 2. The next difference should be 10, so: \[ 20 + 10 = 30. \] Thus, the next number in the series is 24.