$=\frac{3}{2}×\frac{1}{2}×\frac{4}{3}×\frac{2}{3}×...×\frac{100}{99}× \frac{98}{99}\ $
$=(\frac{3}{2}×\frac{2}{3}) × (\frac{4}{3}×\frac{3}{4}) × ….. ×(\frac{99}{98}×\frac{98}{99})×(\frac{1}{2}×\frac{100}{99})$
$=\frac{1}{2}×\frac{100}{99}$
$=\frac{50}{99}\ $