It is fairly common that Kumon students will have been shown to calculate column addition or subtraction with carries or borrows in school. The reason that Kumon Instructors will ask students to do these calculations without the carries or borrows is that we aim to develop students in certain abilities as they progress through the programme.
Doing calculations without carries and borrows is a more advanced calculation skill and by working in this way a child expands their mental capacity and develops greater mental agility as compared to the child who needs to write down carries and borrows. As the child progresses through the Kumon programme, the calculations and topics become more complex and a child dependent on coping strategies for calculations will find the Kumon journey quite challenging. This is because instead of being able to focus all their energies in self-learning new and more complex topics, this child will also have to cope with basic calculations, which may then take away the joy of learning.
In terms of Kumon, the main objectives are to maximise students’ ability and to develop students towards self-learning. As a result we aim to develop strong individuals who can tackle challenges independently. Writing carries and borrows is a perfectly acceptable way to do calculations. However in seeking to maximise each child’s ability, at Kumon we encourage students to use their mental calculation skills.
Overall, we encourage students to answer questions in the quickest or most efficient method. In this case, calculating without carries is the most efficient method as it enables students to develop the number sense and calculation skills that they will need later in the programme, when answering questions on the four operations and factorisation for example.