Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?

Look at this series: 53, 53, 40, 40, 27, 27, ... What number should come next?

2) In the following number series a wrong number is given. Find out the wrong number. 150, 450, 750, 1060,1350,1650,1950

3) 4, 8, 10, 14, 16, 20, ?

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

5) 6, 13, 28, 59, ?, 249.