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

Look at this series: 7, 10, 8, 11, 9, 12, ... What number should come next?

Look at this series: 1.5, 2.3, 3.1, 3.9, ... 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: 8, 6, 9, 23, 87 , ... What number should come next?

Look at this series: 8, 22, 8, 28, 8, ... What number should come next?

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

Look at this series: 36, 34, 30, 28, 24, ... What number should come next?