After the flood ended and the water level dropped, all the animals had to be dispersed throughout the world. Noah stopped at the top of Mount Ararat and caused half of all the beasts plus one to disembark. He then headed for Everest, where he left half of his remaining animals plus one. He then arrived at Popocatépetl, at the summit of which he left half of the animals that remained on board plus one. He did the same on Kilimanjaro and left the last 10 on Mont Blanc. How many species of animals did he manage to save? This is a book to play while you learn to solve problems and do mathematical calculations or, if you prefer, to learn mathematics while you play. If you think that your knowledge is insufficient or that you have forgotten it over time, you are wrong! The purpose of Marie Berrondo Agrell lies in highlighting the playful part of solving any riddle and in infecting you with her foolproof enthusiasm.