Among (3/5), (7/8), (13/64), (8/15), (19/20), how many cannot be reduced to finite decimals.
在(3/5)、(7/8)、(13/64)、(8/15)、(19/20)中，不能化成有限小数的有多少．
<gadget id="calculator">8 / 15</gadget>
<output>8/15 = around 0.533333</output>

<result>8/15 = around 0.533333</result>