52×21=
\( \frac{2}{5}\times\frac{1}{2}= \)
\( \frac{2}{4}\times\frac{4}{5}= \)
\( \frac{2}{3}\times\frac{1}{4}= \)
\( \frac{2}{4}\times\frac{1}{2}= \)
\( \frac{2}{3}\times\frac{3}{4}= \)
\( \frac{6}{8}\times\frac{5}{6}= \)
\( \frac{1}{6}\times\frac{2}{3}= \)