Look at this series: 2, 1, (1/2), (1/4), ... What number should come next?

Look at this series: 21, 9, 21, 11, 21, 13, 21, ... What number should come next?

Look at this series: 22, 21, 23, 22, 24, 23, ... What number should come next?

Look at this series: 2, 6, 18, 54, ... What number should come next?

Look at this series: 2, 4, 6, 8, 10, ... What number should come next?

Look at this series: 8, 6, 9, 23, 87 , ... What number should come next?

Look at this series: 58, 52, 46, 40, 34, ... What number should come next?

Look at this series: 201, 202, 204, 207, ... What number should come next?