Random Puzzles 

Workings

Hint
Denise had strawberry juice.

Answer
Alice had blackcurrant juice and scones.
Jane had orange juice and muffins.
Denise had strawberry juice and cake.
Frankie had blueberry juice and toast.

Workings

Hint
A very tricky puzzle involving prime numbers.

Answer
101.

These are prime numbers, which, when reversed, are also prime.

Workings

Hint
There are two different methods, one involves a cube root, and the other doesn't require a calculator.

Answer
9 x 11 x 13.

Reasoning #1
We're after three numbers that multiply together, so a good place to start is the cube root of 1,287, which is roughly 10.88.

Let's try dividing by the closest odd number to 10.88:

   1287 ÷ 11 = 117

We're now after whole divisors of 117. Trying the odd numbers either side of 11 might work.

Trying either 9 or 13 gives the answer:

   9 x 11 x 13 = 1,287

Trying the closest odd number to the cube root always works, and the other two numbers are the odd numbers either side.

Reasoning #2
We after three numbers that multiply together, but none of these can end in 5 (otherwise our answer would end in 0 or 5).

So, they can only end in 7, 9, 1 (e.g. 87, 89, 91), or 9, 1, 3 (e.g. 89, 91, 93).

However, if they ended in 7, 9, 1, the answer would end in 3 (because 7 x 9 x 1 = 63).

Therefore, they end in 9, 1, and 3 (because 9 x 1 x 3 = 27).

The first numbers we can try are 9, 11, 13:

   = 9 x 11 x 13
   = 99 x 13
   = 100 x 13 − 13
   = 1300 − 13
   = 1,287

A calculator is not required!

Workings

Hint
The final word starts with AI.

Answer
Isle becomes aisle.