Refill for Insta Square by Martin Lewis - Trick50 more refills for your Insta Square You show a blank grid, drawn on your pocket notepad, and ask someone to call out a number. A wave of a pen and the grid visibly fills with random numbers. You then tear off the sheet, sign and date it, and give it to the stunned spectator, showing them sixteen different ways the Magic Square adds up to their chosen number. A memorable magic souvenir.