What is the salt measurement in hypersaline

What will come in place of the question mark (?) in the following series?

4, 8, 2, 12, 1.5, ?

84, 63, ?,  283.5, 1701

324         972         486         1458       729         ?

96 89 ? 90 94 91

252, 235, 220, 207, 196, ?

What will come in place of the question mark (?) in the following series?

112, 123, 144, 169, 190, ?

63, 74, ?,  129, 173, 228

14.8% of 7200 – 16.4% of 6200 + 15.09% of 8100 = 10% of ?

What will come in place of the question mark (?) in the following series?

146, 122, ? , 74, 50, 26

11, ? 220,   660,  1320,   1320