Learn to add and subtract in your head by imagining an Abacus to calculate the result.
Learning to use an Abacus is bo.
Answers to all work is included.
Clearly written with graphics. 2)The accompanying Instruction book \'Imaginary Abacus - Instruction book\' (sold separately).
To follow this course you will also need: 1) A Japanese Abacus (with at least 13 columns).
Example: Learn to calculate 415-350+233-155+44 quickly, just by imagining an abacus.
This workbook has 1882 problems with answers.
Learn to add and subtract in your head by imagining an Abacus to calculate the result