Solution:
Two patterns alternate here, with every third number following the alternate pattern. In the main series(1st series) 4, 7, 10,13, 16 ..... beginning with 4, 3 is added to each number to arrive at the next. Secondary series (2nd series): 26, 20, ... beginning with 26, 6 is subtracted from each number to arrive at the next. Therefore Next two number is 19(from 1st series), 14(from 2nd series). 19,14

Solution:
The correct pattern is + 63 , + 53 , + 43 , + 33 , ............ So, 521 is wrong and must be replaced by (498 + 33 ) i.e., 525.

Solution:
This is an alternating addition series, in which 10 is added, then 5, then 10, and so on.

Solution:
The given sequence is a combination of two series:I. 0, 3, 8, 15, 24, 35 and II. 2, 5, 10, 18, 26The pattern in both I and II is + 3, + 5, + 7, + 9, .........So, in II. 18 is wrong and must be replaced by (10 + 7) i.e., 17.

Solution:
Here, there are two alternating patterns, with every other number following a different pattern. The first pattern begins with 13 and adds 2 to each number to arrive at the next; the alternating pattern begins with 29 and subtracts 3 each time.

Solution:
This is an alternating subtraction series, which subtracts 5, then 2, then 5, and so on.

Solution:
The pattern is +2,+4,+2,+4, So, missing term = 25 + 4 = 29