Different methods of subtracting are described; the equal additions and the decomposition methods are discussed in detail. (DT)

Two sequences of activities were developed to provide instruction on the algorithms for addition and subtraction of two-digit numbers. In the integrated sequence (I) the mechanics of "carrying" and "borrowing" were treated as a single process "regrouping." In the sequential treatment (S) the addition algorithm was developed before the subtraction…

Two sequences of activities were developed to provide instruction on the algorithms for addition and subtraction of two-digit numbers. In the integrated sequence (I) the mechanics of "carrying" and "borrowing" were treated as a single process "regrouping." In the sequential treatment (S) the addition algorithm was developed before the subtraction…

Four algorithms for subtraction are described: borrow and pay back,'' equal additiions, shopkeepers' subtraction,'' and decomposition. (DT)

Early calculating methods and devices are discussed. These include finger products, the abacus, ancient multiplication algorithms, Napier's bones, and monograms. (MP)

This investigation concerns the repeated application of the rule "take the sum of the squares of the digits." (MP)

This article explains the generation of Kaprekar's constant in terms that upper elementary pupils can understand. The procedure is explained and the result proven. This is an example of a new, interesting problem for students that gives them drill in subtraction at the same time. (LS)