Off-balance-sheet calculation refers to the separation of single digits from tens and hundreds of digits in operands during arithmetic operation, which makes the calculation process more convenient. For example, an addition formula 35+47 can be divided into 30+40 and "5+7" through parting calculation. First calculate the sum of ten digits and hundred digits, then calculate the sum of single digits, and finally merge the results. This method can make it easier for junior two children to understand and master the calculation method of addition and subtraction, and gradually improve their calculation level.
In the second grade of primary school, parting calculation can be applied to addition, subtraction, multiplication and division, which can effectively improve children's mathematical understanding and calculation ability and lay a good foundation for further mathematical learning in the future.