Look at this series: 31, 29, 24, 22, 17, ... What number should come next?

Look at this series: 3, 4, 7, 8, 11, 12, ... What number should come next?

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

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

Look at this series: 544, 509, 474, 439, ... 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: 1.5, 2.3, 3.1, 3.9, ... What number should come next?