Every number is the sum of previous two numbers.

1, 1+1=2, 2+1=3, 3+2=5, 5+3=8, 8+5=13, 13+8=21.

Every number is 2 more than the preceding number.

                           3               5              7               9             11            13              

            Difference:                2              2               2              2               2         

The difference between the numbers follows another series-0, 1, 2, 3, 4, 5, 6, 7.

                                         2             2            3            5           8          12        17        23

                    Difference:              0             1            2           3           4           5          6

The number series follows sequential prime numbers. So, next prime number is 13.

Prime Number: The number which can be divided by only 1 and by that number only.

The above series is the cube of each natural positive number starts from

1, 1³=1, 2³=8, 3³=27, 4³⁼64, 5³=125, 6³=216.

In the number series every 2^nd number is 1 less than the first number.

In the number series the difference between the numbers is 9.

                       12          19           28           37            45          54 

        Difference:               9             9             9              9              9  

The number series follows the following rule

1³- 1= 0, 2³- 1= 7, 3³- 1= 26, 4³- 1= 63, 5³- 1= 124, 6³- 1= 215

The number series follows the following rule

1st number = 7
2nd number = 7 x 2 -1 = 13
3rd number = 13 x 2 - 1 = 25
4th number = 25 x 2 - 1 = 49
5th number = 49 x 2 - 1 = 97

6^th number = 97 x 2 – 1 = 193

The number series follows the following rule

1st number  = 1¹=1
2nd number = 2²=4
3rd number  = 3³=27
4th number  = 4⁴=256
5th number  = 5⁵=3125