For (1), w , multiply numeratois and denominators. For (2), students are taught to divide
the 3 into the 6 first. Thus this problem, which differs from the first problem only in there being
a 6 instead of a 4, we do differently. In contemporary parlance, we use a different algorithm.
For (3), we do no division. The "reliable and efficient"procedure is to ignore the 3s and just
write down 2.5 To do (4), another algorithm is needed because there is only one denominator.
For many students, the missing second denominator is intolerable. ‘They need to change 4 to 4.1
before they can do the multiplication. That is, they add another step, to rewrite the original
problem so that they can apply the first algorithm. In contrast, skilled arithmeticians simply
multiply the 2 and 4 and put the answer over 3. The multiplication in (5) requires still another