Account within 100. Workbook

The book is structured as an underwater adventure in which the child, along with the heroes - the octopus Inki, the sea star Selia, and the perch Bob - embarks on a mysterious Ocean of Calculations. Each chapter is a... new story and a new math problem: they need to charge up with the energy of numbers, solve the mystery of caviar, navigate through a coral maze, repair a destroyed reef, outwit the squid, and even win a math tournament.
 
The plot resembles a marine quest: to complete all stages and save the ocean from the black bubbles, the child must not only solve problems on addition, subtraction, multiplication, and division, but also think logically, compare, find the right paths, exclude incorrect options, and test their hypotheses.