Random Puzzles 

Workings

Hint
Do leap years make a difference?

Answer
Hours in 10 years.

Reasoning
In a day, there are 60 x 60 x 24 seconds = 86,400 seconds.

In 10 years, there are 10 x 365 x 24 hours = 87,600 hours, which even without the leap years is already the larger number.

Workings

Hint
There are no missing letters.

Answer
All good things come to those who wait.

The first and last letters of each word have been exchanged.

Workings

Hint
Only the first letter is important.

Answer
3,000 miles.

Take the alphabetic position of the first letter, halve, and then multiply by 1000.

You could also multiply by 500 instead.

Double-Checking
F is the 6^th letter of the alphabet, halving gives 3, multiplying by 1000 gives 6000.

Workings

Hint
This is a well-known sequence.

Answer
R.

The last letter of September.