There are many ways to teach numbers to kids. Abacus is a great tool to teach your child simple math such as counting, addition, subtraction, multiplication, and even division. This is the “A” book of Level-2, which contains Plus and Minus of double-digit numbers. It also has mental maths questions that a child is required to do mentally. It helps in the whole brain development of a child. These Books are very attractive and of very good quality. A detailed explanation may be seen at the universal abacus app.