Brain Teasers and Puzzles 

Workings

Hint
This question involves the months of the year in some way.

Answer
4 3 1.

Reasoning
This is the sequence of the length of the name of the month, and the number of days in that month.

7 3 1 = January, which has 7 letters, and 31 days.

8 2 8 = February, which has 8 letters, and 28 days.

5 3 1 = March, which has 5 letters, and 31 days.

5 3 0 = April, which has 5 letters, and 30 days.

3 3 1 = May, which has 3 letters, and 31 days.

4 3 0 = June, which has 4 letters, and 30 days.

Which means the next three digits are:

4 3 1 = July, which has 4 letters, and 31 days.

Workings

Hint
Can you see 1, 2, 3, …?

Answer
46.

Reasoning
Take the numbers in pairs, square the first, and reverse the digits.
1  1   (1 x 1 = 1,  reversed is 1)
2  4   (2 x 2 = 4,  reversed is 4)
3  9   (3 x 3 = 9,  reversed is 9)
4  61  (4 x 4 = 16, reversed is 61)
5  52  (5 x 5 = 25, reversed is 52)
6  63  (6 x 6 = 36, reversed is 63)
7  94  (7 x 7 = 49, reversed is 94)
   so we require:
8  46  (8 x 8 = 64, reversed is 46)

Workings

Hint
How many hands did the first person shake?

Answer
190.

The first person shook hands with 19 others, the second had already shook hands with the first and therefore shook 18 hands, etc:

19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 190

Workings

Hint
Write the numbers without any spaces.

Answer
02.

These are the numbers 10 11 12 13 14 15 16 17 18 19 20 21 22, but spaced incorrectly.