Solution:

5

23-2=21
21+3=24
24-5=19
19+7=26
26-11=15
15+13=28
28-17=11
11+19=30
30-23=7
7+29=36
36-31=5


(2,3,5,7,11,13,17,19,23,29,31,37,41,43... are Prime Numbers)

Solution:

The answer is 1

6 {6^1}
25 {5^2}
64 {4^3}
81 {3^4}
32 {2^5}
1 {1^6}

Solution:

1806

each number is multiplied by the number+1
1x2 = 2
2x3 = 6
6x7 = 42
42x43 = 1806
1806x1807 = 3263442

Solution:

445

2=(1+1)1
6=(2+1)2
21=(6+1)3
88=(21+1)4

So 445=(88+1)5

Solution:

N for November

M: March
A: April
M: May ....and so on ...

Solution:

794

The nth term in the series is given by the sum of x^n for x in the range 1 to 3, i.e. 1^n + 2^n + 3^n.

Thus the first term is 1^1 + 2^1 + 3^1 = 1 + 2 + 3 = 6,
the second term is 1^2 + 2^2 + 3^2 = 1 + 4 + 9 = 14,
and so on.

The sixth term is then 1^6 + 2^6 + 3^6 = 1 + 64 + 729 = 794.

Solution:

The missing number that fit in ? is 6.

The number in the middle of each triple is the same as the digits of either end's number when added together. 3+7=10=8+2 and so on.

Solution:

143547

Solution:

Each word rhymes with its numeric position in the list. (e.g. 'gun' rhymes with 'one'
etc.)

Solution:

21, 28.

They are the numbers that either contain the digit 7 or are divisible by 7.