Answer:
I am black within and red without; with four corners round about. What am I?
The more you have of it the less you see. What is it?
I start in little but I end in full you'll find me in half and complete.
Though I am only two words I have thousands of letters in me
A prisoner is told 'If you tell a lie we will hang you if you tell the truth we will shoot you.' What can the prisoner say to save himself?
No matter how little or how much you use me, you change me every month.