How do you apply game theory to select who should be on your Christmas shopping list ? Will calculations show Santa is getting steadily thinner - shimmying up and down chimneys for a whole night - or fatter - as he tucks into a mince pie and a glass of sherry in billions of houses across the world?

"A smart, witty, original take on the festive season, with calculations and theories to help you prepare and solve your Christmas conundrums." * The Sun *"Just in case the charm and beauty of mathematical thinking has passed by some of your friends and family, they will be grateful for this slim volume in their stocking. The puzzles and games of Hannah Fry and Thomas Evans involving present-wrapping and Queen's Speech bingo are but an entry drug for heady passages about the natureof truth and game theory." * New Scientist *"From the perfect Secret Santa gift to finally proving the existence of St Nick, a new book uses mathematics to crack the toughest festival conundrums." * Evening Standard *"The broadcaster and author of The Mathematics of Love teams up with a mathematician and writer for this intelligent stocking filler ... sounds enormous fun." * Caroline Sanderson, The Bookseller *