Brain Teasers and Puzzles 

Workings

Hint
The number is less than 100.

Answer
4.

4's double is 8, and 4's quarter is 1.

Reasoning
If the missing number is N, then:

  2N = N + 7
       —
       4

Multiply throughout by 4:

  8N = N + 28

Subtract N from both sides:

  7N = 28

Divide throughout by 7:

   N = 4

Workings

Hint
Do the words make any sense when read another way?

Answer
Ram.

These are the first three letters of the months in reverse order.

Therefore, RAM are the first three letters of March.

Workings

Hint
Light travels around 186,000 miles each second.

Answer
Miles that light can travel in 3 minutes.

There are 31,536,000 seconds in a typical year, and light can travel about 33,530,831 miles in 3 minutes.

Workings

Hint
Find the weight of the bottle first.

Answer
24 ounces.

The bottle weighs 16 ounces.

Reasoning
As a bottle (B) weighs eight ounces plus half a bottle, we can write this as:
   B = 8 + ¹/₂ x B
  ¹/₂ x B = 8
   B = 16

As the bottle weighs 16 ounces, a bottle and a half weighs 16 + 8 = 24 ounces.