4Â Â Â Â Â Â Â Â Â Â Â Â Â Â 7Â Â Â Â Â Â Â Â Â Â Â Â Â Â 24Â Â Â Â Â Â Â Â Â Â Â 91Â Â Â Â Â Â Â Â Â Â Â 462Â Â Â Â Â Â Â Â Â 2763
18       a              b             c              d             e
 What would come in place of c?
The above series go in the following sequence. 4 × 2 – 1 = 7 7 × 3 + 3 = 24 24 × 4 – 5 = 91 91 × 5 + 7 = 462 462 × 6 – 9 = 2763 Hence, the resulting series would be: 18   35 108  427214212843