What should come in place of the question mark (?) in the following number series? 697 553 453 389 353 (?)

The series is as follows starting from the second number denote the previous number in the series by x. x × 1 + 1 × 7, x × 2 + 2...

The series is as follows starting from second number x × 1 + 12 , x × 2 + 22, x ×3 + 32, x × 4 + 42, x ×5...

(c) The given number series is based on the following pattern: 18 × 2 + 2 × 1 = 38 38 × 3 + 3 × 2 = 120 120 × 4 +...

(c) The series is as follows × 1 + 2, × 2 + 3, × 3 + 4, ...

(b) The series is as follows  × 0.5 + 0.5, × 1 + 1, + 1.5 + 1.5, ....

(a) The series is as follows x2x1/3,x4x1/5,.......

(b) The pattern of the series is as follows × 12, × 22, × 32, × 42, × 52 Hence, required number = 1728.

(d) The pattern of the series is as follows : 8 × 2.5 = 20 20 × 2.5 = 50 50 × 2.5 = 125  ? = 125 × 2.5 = 312.5

(b) The given number series is based on the following pattern: 12 × 0.5 + 0.5 = 6.5 6.5 × 1 + 1 = 7.5 7.5 × 1.5 + 1.5 = 12.75 12.75 ×...

(e) The pattern of series is as follows : 12 × 1 = 12, 12 × 1.5 = 18, [0.5 + 1 = 1.5] 18 × 2.5 = 45, [1+ 1.5 = 2.5] 45×...