A comparison of two methods of compound subtraction: decomposition and base-complement addition

Abstract

The 4-week study investigated which of two methods of Compound Subtraction, ‘Decomposition': (DEC, a conventional algorithm) or ‘Base-complement Addition' (BCA, a non-conventional algorithm), effected a better change in two randomised groups of 36 primary three subjects (BCA-17, DEC-19) on the measures of accuracy, understanding, retention and speed, involving whole numbers. The subjects were selected from the then seven existing primary schools (6 public, 1 private) all at Breman Asikuma in the Central Region of Ghana. The t-distribution, involving the difference between means, was used to analyse the results of subjects on the measures of accuracy, understanding and retention while the median test was used in analysing the speed tests, all at the 0.05 level of significance. The study revealed some inherent potentialities for the BCA algorithm and could be implemented side by side with the DEC algorithm. It is also anticipated educational planners, curriculum developers and Mathematical Associations of the sub-region could access the BCA algorithm for its large-scale use. Among recommendations made was the need to embark on a large-scale comparative study using subjects without fore-knowledge of the DEC algorithm. None of the results was significant in favour of either the DEC or BCA algorithm on all four measures.

Mathematics Connection Vol. 3 2003: 75-92