This is one of a series of monographs developed by teachers in schools near Leeds, England. This volume focuses on recommended methods for teaching operations with whole numbers, fractions, decimals, and percentages. For children to attain confidence in dealing with arithmetical processes, it is considered important that they not be confused by changes in methods or modes of presentation which they might encounter on transferring to a different school or teacher. Thus, certain methods are recommended to encourage some measure of uniformity of practice in primary, junior, and middle schools. The sections consider the four rules applied to: whole numbers; fractions; decimals; decimal presentation of metric units; money; and conversion of decimals, fractions, and percentages. (MNS)