Additive or subtractive. In an additive or subtractive strategy the child clearly
identified the use of repeated addition or subtraction to calculate an answer. Intermediate sums or differences were reported and incremented. For example, in calculating four groups of five, the child might have said, “Five plus five is ten, ten
and five is fifteen, and fifteen plus five is twenty." If physical materials were used,
they usually represented a tally of the number of repeated additions or subtractions