which one of the following is the major function of

Find the wrong number in the given number series.

1800, 300, 60, 15, 5, 1.5

Find the wrong number in the given number series.

253, 542, 216, 579, 179, 620

259, 372, 495, 618, 741, 864

24, 72, 36, 112, 54, 162

7, 27, 10, 32, 17, 37

Find the wrong number in the given number series.

1600, 800, 1200, 400, 100 , 12.5

5000, 4500, 3600, 2480, 1512, 756    

45, 54, 66, 84, 99, 120, 144

Find the wrong term in the given series below.

1024, 130, 34.5, 19.25, 21.5, 44.55