Number Series Questions

Here the number follows the given rule 

 $$\begin{gathered} 23-1, 33-1, 43-1, 53-1, ... \\ \end{gathered}$$

But 28 has been given in problem series.

so 28 is wrong number.

The given series follows a pattern that,

19 x 19 x 19 = 6859

18 x 18 x 18 = 5832

17 x 17 x 17 = 4913

16 x 16 x 16 = 4096

15 x 15 x 15 = 3375

So, the missing number in the given series = 4913  

Clearly, the numerators of the fractions in the given sequence follow the series of 2, 3, 5, 7,... and the denominator follows 3, 9, 27, 81, 243, ...
Then, the next term in the given sequence is  935 = 9243 = 127 .

Here the series of the form is x2 - 1, x2 - 2, x2 - 3,...

 53 x 2 - 4 = 106 - 4 = 102

The given number sequence is 101, 98, 93, 86, 75, ?

101

101 - 3 = 98

98 - 5 = 93

93 - 7 = 86

86 - 11 = 75

75 - 13 = 62

Here the series follows a pattern that consecutive subtraction of prime numbers.

Hence, the next number in the sequence is 62.

Clearly, alternatively we add and subtract 10% of a term to obtain the next term of the series.
Thus, 10000 + (10% of 10000)= 11000;
11000 - (10% of 11000) = 9900;
 9900 + (10% of 9900)  = 10890;
10890 - (10% of 10890) = 9801.
 9801 + (10% of 9801)  = 9801+980 = 10781.
So, missing term = 10890- (10% of 10890)= 9801.

Here 2nd number = (1st number x 1 )+1

 3rd number = (2nd number x 2 +2) 

4th number = (3rd number x 3 )+3 and so on..

Therefore, 5th number = (4th number x 4) +4 =57 x 4 + 4 =232.

The first digit is formed by adding the numbers which are the results of powers of 2 increased by one and second letter is the corresponding alphabet to that number...last number is the next number to the first one...therefore

15=7+8 (i.e. 2^3)

O is corresponding alphabet to 15

and 16 comes after 15