The language of numbers is universal: it crosses cultures and continents. Like all languages not native to the speaker, the language of numbers must be learned, and The Butterfly Arithmetic sets out to teach it. Irina Tyk introduces children to the four functions of arithmetic in a simple, practical and non-theoretical way. The Butterfly Arithmetic demystifies what may appear to the young child as a maze of numbers whose relationship with one another is unclear. It can be used with children of four upwards; it is not necessary for the child to be able to read, if a parent or teacher reads and explains the instructions. The book may be used with children of any age who are struggling with the four functions of arithmetic: it is never too late to lay the foundations! The Butterfly Arithmetic emphasises the importance of mental arithmetic, and is not designed to be used with calculators. Just as proficiency in language is not dependent on constant use of a dictionary, so proficiency in maths should not depend on calculators. Ponti Panda, who helped children to read in The Butterfly Book and to understand the use of language in The Butterfly Grammar, returns to help young mathematicians with his musings on how to count matches, marbles and even the stars in the sky. He is joined by the Numbers Family - Mr Addition, Miss Subtraction, Mr Multiplication and Mrs Division - and the strange creatures from planet Marzipo, where there are five days in the week and the Marzipans have birthdays only every five years.