PLAYING WITH MATH it’s an educational path of math created by Fausto Presutti. Its efficacy has been proved by hundreds teachers in primary and secondary school. The educational path is composed by 19 books with different didactic path of mathematic, full of game-exercise that allow children to develop psycho-cognitive abilities and mathematic knowledge. Playing with Math 8 - THE ADDITIVE WORLD WITHIN 100 AND IN COLUMN CALCULATION is based on 42 game-exercise cards. The formative path of this book is structured with these conceptual areas: Pp. 4-7 Correspondence between quantity and number within 100 and coding in the table with tens and units Pp. 8-14 Addition and subtraction by grouping and amount tabalution within 50, without changes of units into tens or tens into units Pp. 15-25 Addition and subtraction by de-composition of tens and units within 100 calculation and with algorithm calculus Pp. 26-29 Addition and subtraction using direct, cyclic and chained mathematical machines within 100 calculation Pp. 30-37 Addition and subtraction using tables and in line calculations within 100 with changes of units into tens or tens into units Pp. 38-39 Graphs, acquisition of calculus rules in the additive world Pp. 40- 44 Numerical equalities with addition and subtraction within 100 Pp. 45-50 Pyramids of decomposition with addition and subtraction and calculus within 100, Problems.