Random Puzzles 

Workings

Answer
6423 = 109,191 ÷ 17.

The numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 have been replaced by 7, 1, 8, 2, 4, 3, 5, 0, 6, 9 respectively.

Workings

Hint
A little algebra might help.

Answer
I have 14 apples, and you have 28 apples.

Reasoning
We can work this out with a little algebra. I have A apples, and you have B apples, then
[1]  5 x (A − 7) = B + 7

[2]        A + 7 = B − 7

From [1] we have:

    5A − 35 = B + 7
[3]      5A = B + 42

From [2] we have:

[4]  A + 14 = B

We can then use [4] in [3] to give:

  5A = (A + 14) + 42
  5A = A + 56
  4A = 56
   A = 14

Which gives B = 28 (by [4]).

Workings

Hint
Adults have fewer bones than children.

Answer
Days in a year.

There are usually around 206 bones in an adult human body, and 365 or 366 days in a year.

Workings

Hint
This is quite a common list.

Answer
T.

The first letters of playing cards in descending order of value.